I do honestly think that ooRP viciousness is more of an issue than inRP...abuse? Overuse?
Some people do have characters that swear like sailors.
I just still really don't understand where you're coming from. What you're saying makes sense, but the why is still unclear, other than "show you can obey server rules and that you know IC isn't the same as OOC."
I'm not sure what swearing has to do with either of those. If it weren't a rule, then the first point wouldn't matter, anyway.
The compromise I would like most would be no swearing on the forum outside of RP channels, or perhaps no swearing ooRP at all. Though, despite what you are saying, I still feel we would be better off without the rule.