No support, sorry. It's a cool idea, but part of a Moderator's job already is to deal with what goes on in the SB. This includes arguments.
Arguments don't have a place in the SB if they start getting out of hand, making other users uncomfortable, or are of a very personal nature, so I don't think having someone to mediate it would help-- they should simply be told to take it somewhere else or drop it if they reach a point where they're encroaching on other users' comfort.
And in my opinion, telling them to take it somewhere else should be enough. It shouldn't be another person's job to set up a chat room for two fighting users; that's their issue to deal with, and they should be mature enough to find a way to continue it if they really need to. Staff aren't parents to make two kids sit down and force them to work it out. ^^;
I understand where you're coming from since there's occasionally some really bad drama in the SB, but I feel as if it would be a very redundant department since once an argument reaches a point where it NEEDS mediating, it shouldn't be in the SB at all.