The fact is that if someone's preferred solution is instead to police people coming into the room on the basis of their "perceived femininity", they are asking for enforced sex essentialism.
Personally, I would rather see THAT sort asked to go piss on a tree.
You do know that humans are really, really, really good at determining the actual real sex of other non-juvenile humans, don't you? It's not like it's some mystery. It's not like we're all standing around saying "oh, that person has long hair, I bet they can gestate babies even though they're shaped like an inverted triangle, with a waist below their belly button, shoulders like a linebacker, a square jaw, heavy brow, and lots of lush body hair!" If a female-women puts on tennis shoes and jeans, she's not suddenly mistaken for one of the guys.
We can almost always tell other people's sex. You know we can tell. They know we can tell. You know that we know. We know that you know. We know that you know we know.
I'm not going to play this game of commenting on how elaborate and ground-breaking the emperor's outfit is and pretending his bare ass isn't hanging out.