Gee, Mr. Linden, I'm sorry we women have encroached so much on your world. I guess we should all go back to the kitchens and bedrooms where we belong, and not trouble you by desiring to hunt, or box, or join the armed forces, or learn to defend ourselves against predators.
Really, I have no problem with sex-segregated organizations of any type. But it's supremely irritating to hear a guy say he doesn't want women around because of PMS. Really, why not just say your dojo is male-only because you believe it provides a different kind of discipline than can be found elsewhere? That would be true enough, and you wouldn't sound like you were lamenting the fact that you happen to live in a time and place where women are no longer under an oppressive boot which limits what they can do in their lives.