Orientation is what arouses (men, women, homosexuals, animals, etc.). Whether or not sex occurs is irrelevant, as long as there is arousal.
A person aroused by child pornography or similar fantasies is a pedophile, even if they have never seen a naked child as an adult.
Conversely, let's say a boy was raped by a man. Sex occurs, but the boy's orientation is not gay (he is a victim of a gay man).
In the context of the game, if a man in a female body (essentially a transsexual) is aroused by the idea of having sex with another man, then he is gay.
