@DadJoke - the difficulty in accepting transwomen into socially women-only environments is the moment they step over the threshold, it's not a women-only environment, it's a mixed sex space.
It's like those little secret perfect tourist spots people want everyone to stay away from except themselves - Going there dismantles the reason for going.
There are a lot of different reasons women choose to congregate is single sex spaces. For safety, sure, but also to be somewhere without male socialisation dominating discourse, bonding over shared experiences growing up in a patriarchal society, for mutual support and friendship.
Transwomen do not share these traits or experiences. They are male. Being a less masculine male than society expects has its own significant challenges, undoubtedly. But these are not the battles women face. It's a problem for men to solve together, not for women to be used as Support Humans.
The talk always focuses on transwomen and not transmen, because transmen are in no way a threat to men the way transwomen might be to women (because male violence is real).
And also because pretty much every feminist I know considers transmen as part of feminism, because they are female.