Yeah, and we did not mention option of dating intersex people - so are we discriminating them too? Also, I would prefer to date a man, but not a homosexual man (because in my experience we just dont click in some important aspects), so most probably I would hesitate to date a gay guy (which is totally not the case with bi, bicurious). Am I discriminationg gay dudes then? Of course not.
Speaking about dating transpeople (who are extremely rare here), I would not date an MtF, because I am not really into them, and the numbers of FtMs are even less. If he was hot, sure, why not? But this is again not about someone's trans-ness, but other qualities, like attraction, chemistry and all those deeply hidden, yet very important criteria which everyone of us has inside and which facilities our decision "hot or not...".