Being the author of a personal blog whose output is lazy, at best, I generally don't have to worry about comment policies. My primary "don't be an asshole" rule can be loosely interpreted, but I don't tolerate bigotry, slurs of any kind, name-calling and trolling. Most reasonable adults won't have a problem with any of these restrictions. I welcome dissent as part of healthy discussion, and I acknowledge that not everyone "evolves" at the same pace, which means someone might "get it wrong" now and then. Sometimes that person is me.
It's a little thing called "good faith." I don't expect the worst in people, so I'm not on edge and not willing to raise the ban hammer so quickly. Years ago, when I was a mod at a forum, and when I wrote for a site that had a good amount of traffic, I didn't feel that everyone was out to get me or their fellow commenters, so I modded with a light hand. I came of age with Usenet and primitive forums that required you to write your own code if you wanted to include a link. I'm painfully old school, but this is why I've been pulling away from the feminist/activist blog world at large: everyone looks like a troll until proven otherwise.
I hate the word "PC." I don't hate the action, I just hate the word because it inspires so much animus. "Don't tell me how to think!" Political correctness is about behavior, not thought processes; those can only be changed through reflection and educating oneself. This is a good thing. Forcing your commenters to comb through every word for every nuance of offense isn't.