In my early days as an HR manager I thought I could help these people in my organization to change by reasoning with them. Waste of time. I eventually came to recognize the only way to deal with these types was to warn them, which they always object to in their usual aggressive and insulting way, then to fire them when their behavior didn't change. I didn't fire them because they made me uncomfortable and mad, but because of the havoc they caused among their peers. Otherwise productive people would become intimidated in meetings and distracted from their work - good people began to feel stressed, mistakes increased, and productivity declined.

It's the same on an audio forum. One really obnoxious person can chase away the most knowledgable contributors; the people you most want to be active on the forum. If you delete one of their posts they will use the "censorship" card in subsequent posts to create more havoc. So the best remedy is to warn them privately then ban them permanently.