If a man identifies as a woman, that initially seems like it defies reality, because they are a male, not a female. But advocates of transgenderism have said that gender and sex are not the same thing. Gender is neurological, and sex is biological. And because of that, people have said that the state of your gender is independent of your sex. If it's a different thing, then it's not defying reality to say your gender is different from your sex.
But if you ask most of these people if people should be able to change their skin color, most of them would say no. Some might even go as far as to say that that's racist. But why? After all, you can separate neurological and biological race the same way you can separate gender and sex. If we apply the exact same rules, then a white person who identifies as black is not "denying reality," because their neurological race is independent of their biological race.
And since transgender people are allowed to permanently change their bodies with surgery in order to align their physical form with their gender as much as possible, at least when they're 18, then "transrace" individuals should be able to do the same: tattoo their body all over with the skin color they want.
But in terms of neurological race, how exactly can you "feel" black? Well, the same way you can "feel" female: cultural norms that firmly establish specific ideas with specific genders. Thus, gender becomes apart of our identity. Without this, you become like trees, which do have male and female, but you cannot possibly tell the difference and you don't feel the difference. And yet, race also has cultural norms that firmly establish specific ideas to specific races. It's called culture. There's black culture, white culture, Mexican culture, Japanese culture, etc. So a person can in fact "feel black" even if they are white.
As you can see, the exact same rules can absolutely apply to race, which is troubling for some advocates of transgenderism, because they don't want that, but they do still want transgenderism. The only differences that gender has with race are irrelevant things that do not break the foundation of pro-transracism, such as the strength differences between sexes vs the lack of strength differences between races.
Conclusion: Transgenderism and transracism are approved by the same logic. Therefore, if transgenderism is allowed, transracism should be too.
One can support transgenderism without supporting transracism.
Because they are not same things, no logical contradiction happens if person supports one and not the other.
If person said "I support A", and also said "I don't support A", that would be a logical contradiction.
However, no such thing happens here.
Your argument tries to expose logical contradiction in reasons.
For example, supporting A and not supporting B, is not logically contradictive.
But if reasons for supporting A are same reasons which support B, then logical justification for not supporting B ceases.
However, moral reasons, being arbitrary, always allow exclusions.
For example, person can say "I support transgenderism for these reasons", and those reasons exclude transracism.
So, for example, one can say "Person can identify with what person wants to be, and that becomes person's identity, except when it comes to race".
This produces no contradiction, and is a logical standard which supports transgenderism and doesn't support transracism.
One can raise a critique that this standard is arbitrary, but all standards of reasons to support something are - arbitrary.
So any critique raised against this standard would be raised against any standard.
The original argument is talking about this topic in a practical context. Could a reasonable person in real life practically approve of transgenderism and not approve of transracism at the same time? What sort of logic would that person have to use? And is any one of those potential arguments actually rooted in anything other than a question-begging baseless assertion?
Your hypothetical logically fails because the assertion is baseless, and it therefore falls apart under scrutiny. But this is different from a fact. Because facts are true, they can be asserted outright, and upon scrutiny, the response can simply be "Because it is true." However, someone's opinion about transgenderism and transracism is an opinion, not a fact. Opinions are not things that are justifiable by asserting them outright, they need to be defended. And if the reasoning is circular, then there is nothing that defends it other than itself, creating an infinite regress of things that need to be defended, hence the circle.
That is obviously not a logically sound way to believe something, and it could also collapse if you simply decide to assert that it is not true, since the very existence of the belief was the thing that supposedly kept its foundation which it never really had.
You're completely missing the point of this argument. Anyone with common sense can see that this argument is obviously talking about the practical application of the logic. It's talking about real beliefs that people genuinely hold, not just a hypothetical person who simply decides, completely without basis, to say that transgenderism is good and transracism is bad. I would hope you knew that, but that would mean you've intentionally distracted from the point of the argument to go on about a very obviously bad interpretation of the text.
Instead of doing that, try using common sense so we can actually talk to each other like normal humans, understanding completely what we mean, instead of constantly worrying about how the most subtle nuances of a certain text can be misinterpreted for the purpose of not at all addressing the real argument. It's nothing more than a time-waster, and it defeats the original purpose of the argument existing.