I see all your points. Yes, technically you could actually believe in what you said. In which case yes, banning it would be offensive to you. But in actual fact, you dont, so it isn't. Suppose you made a slur about my religion, I personally wouldn't mind that. But you don't know whether i'd mind or not, so should proceed cautiously. I don't know what a muslim, for example, will or won't find offensive. So I should be careful with all comments, because I don't want to offend.
The editors have a hard time in my opinion. If they leave something up, they might get criticised. The same applies if they delete something. You can't please everyone, you hope that each decision you make is for the best, and won't make you a "narrow minded jerk."
I'm not trying to have a go honestly, but I certainly wouldn't want to be an editor on this site! :)