I'm more of the opinion that it's wrong for a woman to hit a man, but it's more wrong for a man to hot a woman because of the intrinsic physical differences between the sexes. Our that it's wrong to insult someone, but it's more wrong to insult someone based on their skin color or gender. It basically sounds like you're suggesting that ignoring sexism or racism is the way to make it disappear, and I completely disagree worth that notion. People don't change unless there's an incentive (or disincentive) that motivates that change. Fact is, culturally, societally, the disincentive to combat racism and sexism (among other -isms) is to respond more strongly when they occur. It's perfectly reasonable.
As for MZ's comment, I agree that he should be suspended too. What he said about MM, pissed me off, even moreso after he responded further completely unapologetic about it. That crap has no place here.