I have given you a study which shows that swearing in a discussion has no positive impact on your speech. That is a start to show it shouldn't be used in the one circumstance of a discussion.you still have made no case against SWEARS.
Now, passive swearing, not so sure about. It comes down to sociology and psychology more than anything. Could be rather subjective, but then there are still laws that deal with it.
I could end up with an Anti-Social Behaviour Order if I stand in the street swearing. I'm curious if the US has a similar system regarding anti-social behaviour (not just swearing).