the problems id see:

• obviously the harassment and attempted rape itself, regardless of genders involved
• someone in a vulnerable group is punching down
• the bathroom is not designed for universal privacy and safety (having proper walls)

it happening in a bathroom would not be that much of a detail tbh

also all my girlfriends are trans

and cis men are the demographic most likely to be rapists, so vulnerable people (anyone who isnt a cis man) should be able to stay away

so id want my girlfriends safe from them primarily because theyre a way bigger risk

and also claiming that gendered bathrooms are safe because men (or, as seems to be the more common argument, cock havers) will want to rape women (which is taken to mean pussy havers rather than ppl who would be seen as women which is what would actually get them targeted), which erases non-heterosexuals (and being bi, gay, and straight are equally common among trans people), making segregation an invalid “solution”

all genders (and sexes) are capable of rape, but cishet men are the most likely to do it, and a lot more of them are bi/gay than admit it, and also people might rape outside of their sexualities out of power dyamics