Breaking prime directive in not talking about banning details, here, but there have been SO many posts asking about them and in some cases having some misinformation that's being taken to heart.
Crim was not banned for locking the threads, or on the chance that that caused the forum to crash. We don't know exactly what caused the crash. The crash was hardly intentional in and of itself (except on the bizarre .001% chance it was a 'successful' hacking attempt) and we certainly wouldn't have banned for that. However, the rampant thread locking caused a serious disruption to the forums, and with the confusion in the crash (with the locked threads being the last actions logged) at that point we removed Crim's mod status while we tried to figure out what the heck had happened. After we got the forums back up I unlocked the threads again. Crim was still not banned. The banning happened in tandem with GW's following a post on Crim's part that -- and this is my PR side talking -- demonstrated a serious lack of confidence, ahem, in the forum administration, and went beyond that into being seriously inflammatory/insulting. This, coupled with the fact that the thread locking was a very deliberate attempt to disrupt, it was decided warranted banning, by way of enforcing some time away from the forums to cool off. The thread in question was swiftly deleted when both bans went through, and my guess is that as a result some assumptions were made that Crim was banned for "crashing the forum".
The banning is not permanent, on his part or on GW's. They'll have a chance to come back if they want to. What the exact terms of this will be have not yet been determined, but there will be a post in the admin announcement board when they are.
If you have any further questions regarding this situation, please talk to me via PM. I'd rather that these things not be discussed on the boards for the privacy of those concerned.