I will say yes. We have male and female restrooms. I think you can only allow this to be a law if you make it so that gyms can bar males from the gym (to make a female gym) but not so a gym can't bar females. There are plenty of gyms for men.
If you aren't cool with this then we need to only start building UNIsex bathrooms.
Discrimination has a history of MEN keeping WOMEN down. I don't see why women can't have a few things that are just for them. We have Lots of male sports that females can legally be a part of but can't do. So they create a WNBA , LPGA, [INSERT OTHER WOMAN ONLY THING I CAN'T THINK OF CAUSE I AM A MAN]. We allow this already