Zizek begins from a false conflation of trans activism and gender abolitionism. This is a common mistake by cis people, who seemingly want someone out there to abolish gender and assume that trans people will do it for them.
transgender, genderfluid ... up to agender
There is nothing intuitive about putting agender up here as a thing that other identities lead up to, but much of your argument relies upon it.
the so-called postgenderism: a social, political and cultural movement whose adherents advocate a voluntary abolition of gender, rendered possible by recent scientific progress in biotechnology and reproductive technologies
This is not a thing. Sorry. It's a fantasy that does not survive contact with trans people's diverse relationships with gender.
The universal fluidification of sexual identities unavoidably reaches its apogee in the cancellation of sex as such.
Sex is not cancelled simply by embracing its complexity and refusing it as a social category.
the only way to be sexualized in general is to be asexual
What does this have to do with trans?

Part 2: The fantasy rejection of belonging

This is then extended to a fantasy that trans people reject belonging while irrationally being angry at not being allowed to belong. This is based on a fundamental misunderstanding of both what it means to be trans and what it means to belong.
reject any particular “belonging” and to celebrate the “fluidification” of all forms of identity
One can belong within a fluid identity. Belonging is a relationship in context, not an essential fact of one's being. We're going to come back to this difference later, when you bring up class.
This is why it is an utter obscenity to put together elite “nomads” flying around the world and refugees desperately searching for a safe place where they would belong–the same obscenity as that of putting together a dieting upper-class Western woman and a starving refugee woman.
This metaphor does not hold, however, when you consider how desperately trans people want and need to be recognised for who they truly are. This is not a privilege of mobility but a forced state of liminality.
the more marginal and excluded one is, the more one is allowed to assert one’s ethnic identity and exclusive way of life
Who has the power to allow or disallow? When trans people cannot even use the bathroom, who is being disallowed from asserting their identity? The marginalised may have access to a discourse to some degree, but to say that as a trans man I have more right to assert my masculinity that you do as a cis man seems completely nonsensical.
Italians and Irish – maybe; with Germans and Scandinavians it is already problematic
There is a world of difference between Germans talking about their German identity, and Americans of German extraction talking about their white identity. This false equivalence between Asian and German muddles the politics of how racial identities are constructed.
impoverished European countries expect the developed West European ones to bear the full burden of multicultural openness, while they can afford patriotism.
There is no clear reason why patriotism would be in opposition to multicultural openness. Why should any nation be monocultural? How could it be?

Part 3: The bathroom

Zizek fundamentally misunderstands what is at stake when a trans person tries to go to the bathroom.
they feel oppressed by enforced choice (“Why should I decide if I am man or woman?”)
No, people feel oppressed by not being allowed to pee, as just one example. In any case, there is no choice to be made here. One cannot choose to be other than one is. If a person is neither a man or a woman, they cannot change that by simply "choosing a side" -- I guarantee you, 99% of such people have tried -- and furthermore, most trans people *are* either men or women.
If they so proudly insist on their “trans-,” beyond all classification, why do they display such an urgent demand for a proper place?
Because trans describes one's historical relationship with how others have viewed one's gender, not some special gender category of its own.
“I am transgendered, a bit of this and that, a man dressed as a woman, etc., so I can well choose whatever door I want!”
Being perceived as using the wrong bathroom can be a very dangerous thing, and can even result in physical attack. Trans people are just looking for a safe place to pee, they are not making this stuff up as an exercise in self-expression.
Do they also not often find it difficult to recognize themselves in prescribed sexual identities?
This is the nature of heteronormativity -- nobody can perfectly fit within it, hence its power as a coercive force.

Part 4: The animals

Zizek talks about zoophilia for some reason. But let's take this at face value, for the sake of argument.
why not marriages among multiple persons?
How did we get so quickly from the bathroom to the registry office? Slow down, Slavoj!
What justifies the limitation to the binary form of marriage? Why not even a marriage with animals?
In terms of my own private understanding of marriage, I could conceivably marry a herd of sheep if I want to, the question is whether the lack of legal recognition of my marriage has a detrimental effect on my life. In the case of polyamorous marriage between humans, yes sometimes the lack of recognition is indeed detrimental.
Is to exclude marriage with an animal not a clear case of “speciesism,” an unjust privileging of the human species?
By definition, limiting a privilege to humans only is speciesist. Whether or not this is unjust is a different question entirely.

Part 5: 1+1+a

Here we get to the crux of the essay, and it becomes more clear that Zizek is using trans people as objects to demonstrate something about the gender binary as it affects cis people.
Insofar as the other great antagonism is that of classes, could we not also imagine a homologous critical rejection of the class binary?
No, because class identities are forged in contextual relationship to a system of capital.
Lacan already pointed out that the “formula” of the sexual relationship as impossible/real is 1+1+a, i.e., the two sexes plus the “bone in the throat” that prevents its translation into a symbolic difference.
This is fascinating, because you are quite literally reducing trans people to a function that serves to reinforce the heteronormative gender binary, rather than letting them occupy full subject positions in their own right. Why would trans people even need to fit into an equation along side the 1+1? Perhaps it is you who need us to fill in the space between the impossible and the real -- between your failure to perfect normative masculinity, and the reality that you live in the world as a man.
the two lurks beneath.
Why assume that the dichotomy exists in the subjectivity of trans people rather than in the gender binary as a social construct?
I am caught up in anxiety, not recognizing myself in any of the two choices. Again, do “normal” heterosexuals not have a similar problem? Do they also not often find it difficult to recognize themselves in prescribed sexual identities?
Why not give your feelings of doubt the space to ruminate on their own terms, rather than externalising all of this onto trans people? Is there something unsafe about confronting your own experience of this anxiety, and considering that perhaps it does indeed fit into the same continuum of variance as trans identity?
Am I really a man?
I don't know! But perhaps it soothes you to see me walk by, visibly androgynous, and point out "look at how trans people are in passage between the genders and yet insist on using the restroom that fits their identity, how paradoxical".
Both sexes together do not form a whole since something is irretrievably lost in the very division of sexes.
Someone is on the edge of an epiphany here.

Part 6: The discomfort of sitting in your own fluidity

I get the feeling that a much better essay could have come out of Zizek interrogating his own relationship with masculinity, rather than redirecting attention to trans strawmen.
a flat space is created in which the multiple choices that I can make do not bear the mark of castration
When you put it this way it sounds like a pathology, but surely abandoning the fragility of hegemonic masculinity and its attendant castration complex in favour of something more fluid and accepting is a constructive strategy?
From the Lacanian standpoint, nonetheless, the antagonistic tension is irreducible, as it is constitutive of the sexual as such, and no amount of classificatory diversification and multiplication can save us from it.
There is some merit to this, but we must stay with that trouble, rather than abandoning the project entirely and letting the antagonism rule.
as the ultimate result of the subdivision of the whole into its parts, when, in the final act of subdivision, we no longer get two particular parts or elements, two somethings, but a something (the rest) and a nothing.
Holy shit dude it's almost as if your Hegelian dialectics don't really do justice to the complexity and provisionality of identity.
Not only is woman not-man and vice versa, but woman is what prevents man from being fully man and vice versa.
Seriously, you need to sit with this on your own terms rather than projecting it outwards. It is not woman who prevents you from being fully man, it is the impossibility of man itself as a socially constructed category. You are already fully whoever or whatever you are, there is no partiality in selfhood.
there is no third “objective” way
No, but there are more than two subjective ways.
And the third element (the chimney sweeper, the Jew, object a) stands for difference as such, for the “pure” difference/antagonism which precedes the differentiated terms.
Okay cool, so let's go back to you stood in front of the word "gentlemen" and having a moment of anxiety -- maybe this shows that difference as such *is* the universal. Maybe the idea that a 1+1 man+woman dialectic can exist to stabilise society amid a mess of diverse identities is where the entire error begins. There is no need for a third position when the first two positions are impossible.

Part 7: Making sense of oppression

The denouement of this essay is a spectacularly horrid misunderstanding of racist and sexist oppression.
In the space of anti-Semitism, the “Jew” stands for social antagonism as such: without the Jewish intruder, the two classes would live in harmony
Right, so prejudice objectifies the Jew as a scapegoat to make sense of a system based on false dichotomies. Meanwhile, Jews are people who exist and experience the world as Jews, not simply as symbols of antagonistic difference. What could this tell you about Judaism? What might this tell you about "transgenderism"? (By the way, no trans person believes in "transgenderism")
probably in their haste
We have words for this other than "haste". Try "sexism" for a start.
the total transgender “fluidification” of gender
It is interesting that only one paragraph after saying that trans people do not undermine difference but represent it, here you position transgender people as the actors who are "fluidifying" gender, as if something was once stable that is now being undermined.
the black man reported that he experienced the woman’s gesture as a case of racist harassment…
This is very ambiguous. Did he report it as an incident of harassment to somebody in authority? Or did he describe it as an example of a racist microaggression? Conflating the two is not particularly helpful as we try to understand whether harassment is encompassing ever more things within the "PC environs".
it is not difficult to discern in this fantasy of a peaceful world the fantasy of a society without social antagonisms, in short, without class struggle.
I don't think this essay did anything near enough to demonstrate that class divisions and gender divisions are the same.

Posted from Diigo. Other annotated article links listed here.