Nothing would give me greater pleasure than Thompson coming in at least 2nd in SC, but I doubt he will make 3rd.
If Fred publicly calls on the President to withdraw this brief, then he'll score big points with voters. As an attorney, he can explain well why this brief is actually very anti-2nd Amendment.
Further, it is possible that it'll actually get done - I'm not sure that this was even on Bush's radar. It sounds suspiciously like some career gov't lawyer's way of screwing individual rights in a fait accompli. Bush might decide to withdraw the brief if he knows about it, comes under pressure from Republican candidates, and if the NRA actually emails its members and asks them to melt the White House phone lines. Of course, I'm not holding my breath - Bush isn't exactly a friend of the 2nd.