For myself, being in a bathroom or dressing room with a trans woman would not be much of a big deal but I won’t lie and say that I would not be startled to see an unexpected exposed penis or testicles. I’d be more concerned if I felt that I or someone else might be the target of a predatory person, whatever genitalia was present. So yeah, a cis male or female attacking a trans person would definitely be concerning to me. I’ve been pretty fortunate to be able to defend myself and occasionally another person against physical and sexual assault. Not that those experiences don’t leave some trauma/PTSD. But not one of those individuals who attacked me or other girls or women was in a women’s locker room or dressing room or rest room. None of them were trans. I’d put good money down betting that they most likely be dangerous to trans individuals as well as to women. More so, in fact.