First: I have no way of knowing how sick or what his underlying motives are. I am reasonably certain that I don't want to play any more.
That said, I am equally uncertain that shunning or similar is useful either. I would suggest that 'normal' behavior be responded to in 'normal' fashion. Around here 'normal' gives a fair amount of leeway to make a jackass of ones self without undue comment. The games we are sick of, suicide threats, blustering accusations, and such which are now suspected of being role playing, should be COMPLETELY ignored. Such crap should not be rewarded with any recognition whatsoever.
This would reward him for being 'socially sane', if such a concept is realistic, and costs little in the way of overhead when he is being boink-brained. Mind, this is said without knowledge of what he has done to the twiki board, although I noted that a number of his accounts were deleted. I also don't know about the 'mailing list' and whatever went/goes on there. Additional protection may be necessary there...
Personally, I would prefer to err on the side of generosity and free society. This does not mean that I am willing to play stupid games. I am willing to ignore a fair amount though... sometimes, around here, you have to...
my .02..
<insert something nasty, cause this is the flame forum...>