If there are banned subjects on any given forum, it's easy enough for members to set up a temporary forum elsewhere to discuss the issue. It takes a few minutes to set up, is free, and therefore doesn't require a sponsor (which is often the reason behind banned subjects in the first place). When the thread has run its course, you can simply abandon the free forum or keep it on ice until the next banned subject comes up.
http://www.jconserv.net/ is one free forum provider I have used.
http://www.jconserv.net/ is one free forum provider I have used.