I've been evangelizing on IRC about how to handle SPUI for some time now. Basically SPUI is a continuous breaching experiment -- he is constantly testing the limits of our collective patience. He is going to do this; that is the nature of SPUI. The problem is that banning him -- or any sort of long term block -- will just encourage him to try to subvert the system in less obvious ways. It is my opinion that we'd rather have SPUI editing as SPUI rather than as an army of SPUIsocks, which I firmly believe is what would happen if he ever gets blocked (and remains blocked) for an extended time. And we all know how hard it can be to deal with that sort of thing.
Fortunately, one thing about SPUI is that he stops when he finds the boundary. So really all that need be done to manage SPUI is to "smack him on the nose with a newspaper": give him a short block (3 hours to 1 week, depending on circumstances) whenever he goes too far. He seems to accept short blocks in good grace (he knows what he's doing, after all) and after his blocks clear he almost always goes back to his usual editing, which, by and large, is productive and useful.
Psychim complained to me [on June 30th] that if we only block him for a short time when he does these things, then SPUI will have won. This is the real problem here: admins who see this as a contest. Too many people are now trying to "beat SPUI" and that has resulted in a great deal of misbegotten vehemence toward him as a person, rather than at his individual actions. (This is also a large part of the problem with the highway naming case, actually; a number of people opposing him there seem to be opposing his position simply because he's SPUI, and not because of any substantial fault with the position he takes on the substantive issue. The ArbCom should be giving those people a firm rap on the knuckles for making it a dispute of personality instead of a dispute over policy, but I have little hope that that is what you'll actually do in that case.) Many of our admins have decided that he is a troll (and, to an extent, he is, but he's a manageable troll who happens to be useful), and as a result they no longer give him any semblance of good faith even when he is trying to contribute in good faith. To be fair, SPUI brings this on himself by being so tendentious in his breaching experiments, but that doesn't excuse people from treating with him fairly the rest of the time.
Generally put, SPUI is a valuable contributor who is also a low-level annoyance, and our admin corps is not good at managing people like that, because their operational mindset is one of combat instead of one of management. Whenever he goes outside the boundaries of acceptable behaviour, he should be promptly given a short block (from a few hours to a few days, at the longest) with a clear and polite message as to what he did to get blocked. Hauling him before a firing squad for what would otherwise be minor offenses just riles him up more and allows him to start his usual campaigns (which is also why I think short blocks are a good idea; he doesn't have time to build a campaign against the block if it's only for a few hours). Conversely, NOT blocking him for minor offenses encourages him to commit more major offenses (remember, he's seeking limits, and he will continue to probe until he finds the actual limit). Also, he knows that long (and especially indefinite) blocks won't stick anyway.
(Update: Stupid missing parentheses.)