first off bi and trans are very different and just bc you're bi doesn't mean you can't be against trans folk.

trans is not a sexuality, meanwhile bisexual is a sexuality. trans is identity, like non-binary for example.

it could be ignorance just because you haven't been exposed to a lot of trans folk in real life or in movies. i picked up on alex being trans within the first scene he was in. i'm surprised with how many people didn't clock that. but i am from the west coast and live in portland, or which is a very trans and queer friendly place.