

I would argue that in private spaces, absolutely. The owner of a private space has the exclusive right to admit anyone they choose and bar anyone they choose, based on any criteria they wish. [To preempt the obvious objection, I’m talking about e.g. a private residence, not a business.]
I’d argue this is doubly true for support group style groups. If there’s a support group for a topic that is exclusively experienced by one sex, I don’t think it’s at all unreasonable to make that group exclusively for that sex. (Examples might be testicular or ovarian cancer sufferers.)



No, clearly not, as I already addressed. Fuck off.