Equality is a one dimensional metric and a kind of tunnel vision that undermines true ethics. Should a small man eat the same quantity of food as a large man? It would be equal. Have you given away most of your wealth to the poor and needy so that everyone has an equal share? Shall we cut the legs off the tall so that they are the same height as the short? Or throw acid on the beautiful so they have no advantage over the ugly?
But I've yet to hear anyone complaining about boys being intimidated and not participating in a class because it was full of girls being bitchy. And to the extend that it happens (someone mocking an ugly kid in class), I'd assume it'd get slapped down in the same way.
The "masculinity-affirming posturing and violence" that the parent refers to is pretty much entirely negative. There's no benefit to praise, accept, or encourage that kind of behaviour.
Men are interested in doing something and creating something, and we will continue doing this forever. Those who cannot do this will continue to complain and blame someone else for their situation. A lack of personal responsibility (independent of gender) will always result in failure.