Anything that makes it a little harder for people to be creative...I'm against.
Yeah, people do occasionally let their OOC spill into their IC, but we're all writers, and we should be mature enough to look past those moments and focus on the narrative. If someone writes in a way that we can't respond to it...don't. And then stop RPing with that person. These are choices you can make to improve your own RP experience, but there's no need to curtail theirs in order to do that. The only way you get to post whatever you want is if everyone else gets to post what they want. When you're finding someone hard to write with, stop. And if they've offended you, flag it to the Staff, and they can take it further if they absolutely have to. That should be it.
End of the day, it's not much to expect a little maturity from writers around here - and, realistically, if you write with someone being immature and displaying that sort of behaviour, that's when I'd expect you to be the mature party and stop writing with them. When they realise it's ticking people off, they'll stop. Or they'll leave. No need to make a rule out of it - that's proscriptive in a way that just makes a bad atmosphere around here, everyone afraid to write their own way for fear of offending anybody.
While we're at it, we should also ban faction politics, war, combat and any moment where two writers face off against each other. You know why? 'cause it's causing conflict on the board, generates frustration and makes people upset.
That would only cause the site to implode, mind you, but better that than offending anybody, surely?
Or maybe we can all act like adults and just enjoy the writing experience. I don't want to be the one that shortens that down to "get over it", but something tells me that might be the best approach here. Sorry!