I think the real root of what I'm trying to get across in my degendering sports posts is that I want a future where men aren't a class that has power over others, and we'll never get there if we continue to allow places to exclude women, de facto or de jure.
It's not just about sports. It's about spaces that allow men to congregate and perpetuate misogyny as a class. So any space that wants to be safe for women (and trans women) has to be militantly anti-misogyny (and anti-transmisogyny). Men's spaces have proven time and again that they will align themselves as a class against the interests of women, and thus must not be allowed to have spaces to themselves.
The inverse is not true. Women's spaces/sports/programs/etc. work to rectify the class disparity as it exists. Women do need spaces apart from men to escape misogynistic class-motivated violence. Women do need scholarships and sports programs to rectify the economic disparities, both historic and present, to be able to achieve anything like equality in the patriarchal society we all live in.
BUT the division does allow for the continued subjugation of people society deems not to fit into the class of "woman". Spaces designed for (cis) women in the patriarchal structure as it stands will always be aligned against trans women because it is in their material interests.
The goal shouldn't always be spaces and programs to protect the underclass and lift them to the same status as the ruling class. These things are important right now because the disparity exists, but I think it loses the forest for the trees. The end result to work for should be a world where there is no class disparity between women and men, between trans people and cis people, between racialized people and white people, between transmisogynized people and non-transmisogynized people.
That means taking spaces away from the current ruling class(es). That means any space that is accepting of the current ruling class(es) must be militantly anti-racist. Militantly anti-transmisogynist. No one should be denied the bare human necessities (shelter, food, etc), but behaving in any manner counter to the interests of the underclasses as they exist must be completely intolerable.
If you let one Nazi in your bar, you run a Nazi bar. If you let one misogynist in your sports league, you run a misogynist sports league.
I don't want to live in a world where I have to be wary of at least half the population. I don't want to live in a world where any potential friendship I have with a man, or a cis person, or a non-transmisogynized person is tinged with worry because of the class disparity. I don't want to live in a world where my only option for any sense of real security is a community of people marginalized just like me.
Separate but equal is never going to be good enough. I think it starts with dismantling men's spaces.