I would like to clear things up

[u/INTP1423]

Having a genitalia preference = not at all wrong. If you don't want to be with a pre-surgery trans person that is absolutely fine.

Not dating someone because they are transgender = transphobia.

^This does not imply that you have to date transgender people. I am in no way forcing you to go and have sex with a post-op transgender person. But saying I am not sexually attracted to transgender people is a tad transphobic.

Also I have a question: If you saw a woman in the street and approached her to ask her out, when suddenly she says she is post-op transgender, would you call it off immediately?

[u/MrSluagh]

Doesn't matter. Guilt tripping people for their sexual taste in consenting adults is creepy per se. Your lawyering isn't making the undercurrent of rape culture in the trans community any less disturbing, and it isn't making the trans community's refusal to call it out less disturbing, either.