It's solely because they've heard women pointing out the male supremacism underlying the thinking that men's feelings, safety, wishes, dignity and privacy is important but not those of women.
Two seconds reflection would suggest that men's needs for those things can easily be met by third spaces. They have no intention of meeting those women's needs with anything more than derision, abuse and exclusion. And that would be the fundamental belief that men matter and women don't, and it's the job of women to serve men. Women don't want to be served by men with trans identities, they don't want dominance, they just want to be left alone.
So as usual it's a lot of crazy nonsense because it sounds good, and is not comprehended beyond Mummy Says It. You can feed certain online sections of this movement a word and count the days before you see it pop up. It has been done. The word 'coy' was a game played in just that way, and whoops there it was very quickly. I often repress the urge to do it with a made up word and wait to see it appear.