[Crake]

>Given that, why would we expect feminists to be talking about the effect of sexual assault on males?

Because "feminism fights for men too!" is something we hear all the time.

>It's not their responsibility to do so, and I'm absolutely certain that most feminists would not object to male campaign groups which highlight the problem of male sexual assault.

You'd definitely be wrong about that: https://www.youtube.com/watch?v=FWgslugtDow