They should actually understand better than most why we want our own space.
The trouble is that there's a whole new set, who see women's spaces as validation and entitlement, the old 'identifying as' rather than 'identifying with'
These people haven't stopped to think about other people - as seafret says, it's a lack of empathy. I can easily see why various groups might not want me around - even if I really would enjoy their company or want to get involved. I can understand that not everything is about me, that the over-70's swimming club might be happy like that, and not want me butting, or that the men's shed society is happier without me barrelling through the door to talk about brewing beer, AND THAT IS FINE.