Is it homophobic to say you "can't" date someone who is bisexual? Asking for the person on IG who told me it's a "preference"

For context:

The thread has since been deleted, but i have no problem publicly shaming biphobia.

(Sidenote on my last comment: i do feel that refusing to even give a trans person a chance specifically *bc* theyre trans is transphobic. However, I can understand the other side of the argument...

...Transmen are just as man as cismen, but there is an undeniable anatomical difference that is involved. However, if someone is attracted to a specific man (trans or not) and *then* loses interest *bc* hes bisexual, that shit's biphobic...

...Absolutely nothing has changed about him except the gender identity of his (possible) previous partners.)

And while I'm at it, bi people are not more likely to cheat so get out of here with that homophobic bullshit.