I've been idly watching the story, waiting for the smoking gun (so to speak) to appear. Voila!
The lawyers in charge of the case were not responsible for the move, and they actively argued against it. However, they were overridden by Associate Attorney General Robert D. McCallum.
McCallum "is a close friend of President Bush from their days as fellow Skull & Bones members at Yale University and was also a partner at an Atlanta law firm, Alston & Bird, which has done legal work for RJ Reynolds Tobacco, one of the defendants in the case."