I find way more worrying that a random fanatic woman goes around asking to see girl and woman genitals than the idea of sharing a bathroom with another person who happens to pee from a "non-default" pee hole.
But I guess I'm a weirdo so it must be me.
Their hate to trans women comes from the fact that they hate men (probably because of the systematic misogyny of our society) because of unprocessed and unaccepted trauma. They can't (or don't want to) understand that trans women are, in fact, women, so they just focus on them the hate they feel for men. It's just misandry with extra steps.
The problem here is that they are so focused on hating that they can't see beyond it. You can't help someone who doesn't want to be helped.