Troll.
No, a troll is a newbie who drops in to take a dump. This guy's been here far too long to be considered a troll. He's just a POS who knows how to push the envelope just far enough to prevent himself from being banned and who only gets satisfaction from the attention he creates from his inflammatory comments.
In some circles he would be considered an obnoxious attention whore.........(I'll refrain from posting the applicable photo)