At first I thought that a separate forum would be a nice addition but reading some of the responses has made me think about it more. I do like the thread specific banning idea because it still allows users to speak their minds in appropriate threads but could stop some of the rampages that go on in some of these threads. Sometimes people bring good heated discussions to these threads but sometimes it seems like a handful of people just flame each other back and forth. If those people can't control themselves when speaking on a specific subject or continue to show that they will not offer constructive discussions to a topic then they really should be removed from the discussion until they can show they are willing to contribute. This shouldn't be reserved for the haters either, there's been plenty of fans that aren't constructive to a discussion and disrupt a thread with flames/bait tactics. The VG threads aren't the only ones that contain thread warriors but they have been the most prominent ones of late and show an increase in these types of threads.
If Requiem does decide to test it out, I found a user created plugin for that specific feature on the official VBulletin boards.
Ban User From A Thread - vBulletin.org Forum has the plugin and around the 14th page is discussion on making it work with version 3.6.
I don't think the Nerd Rage thread would have really needed a thread specific ban though (I wouldn't use that thread as the measuring stick) because it really was intended for the rickshaw from the start and I'm surprised that it got as far as it did. It served its purpose I suppose; a thread about Nerd Rage will contain Nerd Rage.