doesn’t that mean they’re all “not real”? It seems incorrect to single B out under that logic.

Depends what you mean by "real."

I'd put the alphabet salad on a continuum of delusion, with homosexuality being the most deeply conditioned behavior owing to some sort of early trauma during sexual maturation and trans-sexuality being a purely social disease or "choice," many times coerced in vulnerable adolescents by the tranny political lobby and their accomplices in medicine and psychology.

doesn’t that mean they’re all “not real”?

I don't know. I'd say a "bisexual" is a hetero who likes the occasional homo encounter, or a homo who makes an exception once in a while out of politeness or compassion or curiosity.

Which is to say that I think homosexuality is a more deeply held drive than bisexuality,

Overall, what determines one's sexual preference is a mystery to me, but I am obviously not beyond guessing for the sake of argument.