Hmmm... I dont know.
Dressed as a male, I felt gay having sex with guys. Dressed as a female and having sex with guys didn't feel gay at all. it felt perfectly normal and proper.
I agree that straight guys are more willing to do stuff with a T-Girl than another guy. That's one of the reasons I dressed as a girl. The funny thing is, I didn't have to go full on Samantha, with wig, breast forms and make up for it to work with straight guys. I learned early that wearing a pair of jeans only a girl would wear, like Jordache, American eagle, guess, Vigoss or Maurices and some rather tame eyeliner would be enough for some straight guys to become very interested.