i'm against banning anyone, ever, because i think free speech is important
that said i do think he makes the forum a worse place, and is a really bad narcissist (like on the level of adam coate, mdickie, jforce, tim langdell, etc.), and has a long, long history (10+ years) of acting the same way. so if you do keep him don't expect things to get better, they'll just get worse
one way of dealing with him which was proposed in 2006 or so was to delete any post of his in a topic after the first one. because he basically gives an interesting and insightful opinion in his first post. however, every subsequent post of his in a thread is him attacking anyone who disagrees with his thoughts on a subject.
he also does believe he's superior to most of us (this comes with being a narcissist). he has said he's smarter than 99% of the population, and that if you're poor it's because you're lazy, and he believes that social manipulation of other people is the key to getting ahead, and that people should use each other as tools, not treat each other as friends or equals:
One of the hallmarks of a good social manipulator, is they're better at it than people who think it's "not ok" to do it. There's a reason that such socially intelligent people get farther ahead in society. Namely, that this is half of how the human brain evolved, it's one of the major driving factors in human evolution. No, we didn't just make tools, we used each other as tools.
so basically, if you believe that you should ban people when they disrupt the conversation for their own ends (e.g. spamming) you probably also believe that you should ban people who believe that you should use other people as tools and to manipulate them.
of course i'm an ideologue and don't believe you should ban either disruptive people, trolls, or even non-bot spammers (bots are okay to ban because they aren't people). so now that i've presented the reasons why you might want to ban him, here are the reasons you should not:
he adds things to the conversation which would not otherwise be said, and has a couple unique ideas. some may be crazy and stupid ideas, but they are ideas that would not otherwise be expressed, and variety is important.
he also serves as a mental exercise for users here: it was fun to see supershigi argue against him (as i said, i thought she was "on fire" in her responses to him). she never would have made those amazing posts if he wasn't here to argue with :D
he also adds interest to the forums here. as people have mentioned, they like the forums when they are dramatic / interesting, and what's more dramatic than a self-deceptive, narcissistic troll arguing with everyone? i'm not being tongue-in-cheek, i do think such people genuinely add interest value to the forums and make them more entertaining to read, even while they sometimes disrupt genuine conversation and intellectual progress. basically you're trading boring rationality for entertainment, which is sometimes a good trade. truth usually isn't as interesting as fantasy and illusion, so a dose of fantasy and illusion is okay. the forums are strong enough to handle him.
i'm also a determinist and believe that narcissism is probably due to brain structure and hormones and genetics, not to choice. to at least some degree, he can't help acting the way he acts. so it'd feel bad to me to ban him for something he can't help but do. it's not like he wants to be a jerk, he just *is* a jerk, it's part of who he is on the inside. and it'd be wrong to reject him for who he is.
so my suggestion is threefold:
1) don't ban him, but perhaps give him a special title on the sidebar so that people know he's dangerous to rational thought.
2) unban everyone else who is banned: super joe, cas, kon-tiki, jforce, adam coate, etc. they too add drama to the forums and interest value and say unique things, even though they are disruptive. disruptive people disrupt the boringness of normal people. give them similar sidebar titles.
3) add an ignore feature (a plug-in) to this forum so that people can ignore who they don't like, including the people above. that way you can satisfy the people who don't like being offended. i imagine it's relatively simple to add an ignore plug-in, and an ignore feature is far superior to banning, because it allows individual people to ban those that bother them on a case-by-case basis. perhaps even put them on everyone's ignore list as the default, but allow users to individually "opt-in" to being able to read their posts.
tl;dr version: don't ban him, but give him a warning label on the sidebar, and add an ignore feature to the forums. unban super joe.