"Maybe Liberals Are So PC Because Conservatives Keep Excusing Bad Behavior"
Though you might just as well say: maybe conservatives keep excusing bad behavior because liberals are so PC.
I mean, everybody realizes there's this kind of polarization / oscillation dynamic going on, right? Liberals and conservatives already tend to view these issues differently. Conservatives tend to excuse too much in this context, whereas liberals / progressives tend to imagine transgressions where there aren't any, and indiscriminately throw around false accusations. Each end of the spectrum pulls in its own direction. Conservatives are fed up with liberals' bullshit, and vice versa. Both get worse, and this, in turn, makes the other side worse.
I mean, seriously, everybody knows this, right?
This is a familiar human phenomenon.
I'm not saying the two ends of he spectrum are equally bad. Perfect equivalence with respect to guilt almost never happens. But both sides are pretty damn bad. My inclination is to think that the conservative tendency has done more harm over the long run, but left is currently more intensely about this particular thing. I mean...they're really, really crazy...
But anyway, that's not all that important. What's really important is that every bit of craziness you allow yourself to indulge in is not only bad in itself, but it makes your side more loathsome to the other side, and tends to create a more-or-less equal and opposite amount of crazy on the other side.
So even if you don't care about being a loon, maybe you'll care about that.