Well, it was only half-serious, more an attempt at humor than a substantive point. My full position is something like:
1. If women want to box, that's their prerogative. That doesn't mean we should have professional boxing matches for women. Professional boxing really shouldn't be a thing, given what we now know about brain injuries.
2. Ideally, we wouldn't have men's boxing for the same reasons. If I was king for a day, after I got through doing all the important stuff, if I had time left over I would ban boxing. But in the real world, men's boxing is not going away because it is so deeply ingrained in American culture. Heavyweight champions like Ali, Marciano, Joe Louis, Foreman, and (for good and bad) Mike Tyson have been icons. But the inability to get rid of men's boxing doesn't imply that we should expand boxing more.
3. As for MMA, that ish should be illegal -- though admittedly I haven't watched it in many, many years after being repulsed by the violence when I first saw it. Maybe it's less brutal, though I doubt it. There are probably lots of brain injuries happening.
4. I didn't realize that it would be controversial that people generally like to avoid being drafted into the military during war time. That's not sex-related.