It’s not clear to me if you’re being facetious or sincere with your comment.
From a technical perspective, yes, some gay men are “discriminating” against transmen as romantic and sexual partners. Some are actively choosing against transmen as partners. Other gay men will form loving and/or sexual relationships with transmen. But I wanted to speak to the motives for the rejections.
My point was: I don’t think gay men choosing against transmen as partners can be fully explained by the concept of “transphobia” (fear/hatred of transgender people). Rather, it’s the importance of certain physical features to gay men’s sexual culture and the (probably accurate) assumption that transmen do not possess those physical features. Added to that is gay men’s sexism/misogyny and the expectation that a person’s gender presentation will match their biological sex, and the heightened importance of that expectation in gay men’s spaces.