Personally I'm not a fan of any real world violence against anyone, but to me the gender doesn't matter so much, if a big macho twat were to punch a non-muscular defenseless individual than its despicable regardless of the gender of either party involved. I dunno, maybe I'm just different from everyone and their dog, but I don't see that much relevance in an individuals sex when it comes to behavior. Chivalry is dead, and for good reason, women want equality (which is hardly unreasonable) then the special treatment that is chivalry goes away right along with traditional gender roles and male dominance.
tl;dr version: I guess it is somewhat sexist to think that hitting a girl is any worse than hitting a boy.
tl;dr version: I guess it is somewhat sexist to think that hitting a girl is any worse than hitting a boy.