'Twas brillig, and the slithy toves did gyre and gimble in the wabe

Hmm, interesting question. As one who has maintained community servers in the past, I would have to say that B is taking the 'correct' action. Past evidence states that A was causing trouble, and there is evidence to suggest she/he may still be doing so. Until and unless anything comes out to prove that someone else is causing it, and if listservers continue to mysteriously fall over, he/she should remain banned in my opinion.

That said, of course, I'm notorious for my paranoia when it comes to system security and stability.

HTH. HAND.