[a sign reads FEMINIST CONFERENCE next to a closed door, a blue character shrugs and says…]
I don’t care
[next to the same door, the sign now says RESTRICTED FEMINIST CONFERENCE WOMEN ONLY, there are now four blue characters desperately banging on the door, one is reduced to tears on the floor, they are shouting]
DISCRIMINATION
SO UNFAIR!!!
LET US IINN!!
MISANDRY


I think it’s fine to have women-only or men-only spaces if the goal is to not have the social dynamics of a mixed space for specific discussions. I don’t think that’s discrimination at all, but that word has multiple meanings.
Neither of these are prejudiced. You also wouldn’t hire a cis woman as wet nurse if she couldn’t breastfeed (which is the reason for discriminating) and there certainly are circus acrobats who are wheelchair-bound, it’s just that usual acts wouldn’t work with that, especially not safely.
The other form of discrimination is based on prejudice against a group, no exceptions. It’s not “no because you can’t do X”, it’s “no because you are X”. That’s never a good thing. But it also isn’t necessarily the motivation behind creating an X-only space.