If there were actual consequences for this type of behaviour I'm sure they'd manage to control themselves.
I am not sure this is actually true. My understanding of flashers is that they don't usually have a fetish, generally speaking it's a sort of obsessive compulsive disorder, or like kleptomania, and a lot of them are quite ashamed of it.
It's still a good reason to argue for separate spaces, but I am not convinced that the men who are arguing that they should be allowed into women's spaces are from this group, even the ones with outright ulterior motives.