Or, for that matter, why are there men who tolerate it (standing by and doing nothing) when it happens to OTHER men, as well?

There are those who watch, passively, as women get preyed upon...or participate in it themselves. Many of those same men would shrug and turn a blind eye if they see another iteration of it happen to other men.

Many men, on the other hand, would be the first ones to step in and defend a woman being attacked by a predator...but they would also, paradoxically, demur and "stay out of it" if they see another man sexually assaulted. A misplaced sense of "chivalry," there? Toxically-masculine hysteria about how the assault which is occurring is somehow just "a gay guy thing"...?????

Many women stand up for the targeted person -- female or male -- because they can relate to being ogled, harassed, or assaulted, themselves. But many women would stand up for one of their "sisters" while, again, paradoxically, "staying out of it" if they see similar behavior inflicted upon a man. And then there are women who would partake in the same "victim-blaming" we hear so often from boorish men...where they deem that any survivor (regardless of sex or gender) "should have spoken up sooner" or "shouldn't have put themselves in that position."

When it comes to sexual exploitation, people are fucked up, in general. And, on the flip side, there are those who rise to the occasion of gender-inclusive multidirectional chivalry (which, when you think about it, is the only type of chivalry that should exist in the first place!).