A lot of forums have a tough time with political posts. It is just hard to stay civil, and mods tend to pull he trigger a little more often when their own chains are being pulled, which annoys those doing the pulling even more, and makes it even less civil.
I like a good political discussion, and really I have not seen a whole lot that is real offensive here. maybe it gets deleted before I get a chance to see it.
IMO, creating posting rules that are meaningful is the key. You can't just say it is up to the mod's discretion and have the members feel they are being treated fairly. But writing those rules in a concise and understandable way is not a trivial task.