There is a strange double standard in our society which posits that it is totally reasonable for women, people of color, people of different sexual orientations, etc. to all deserve their own 'safe spaces' to be around people of their intersectional group only; but the moment that males want this, or white people, or straight people, it's exclusionary and offensive. Nobody can defend this effectively without resorting to rhetoric that essentially just attacks people in the latter groups for things that are not their fault individually, and the entire mechanism that works to prevent them from having their own spaces seems fundamentally vengeful.

There is very much a need for boys to have a space to be boys: where they can let their boisterousness out, where they can act a little crazy, or just act closer to their true selves etc. without having to worry about how they're perceived by the girls. As soon as puberty kicks in, all co-ed events are affected by sexual dynamics; it's been a standard in every human society to provide plenty of contexts for boys where that is removed from the mix as much as possible in order to get better / different behaviour from the young cadre.