The initial war was just. If it ended in Tora Bora whether or not Osama escaped it would be the shortest US war instead of the longest. If you kill Osama find the closest Taliban commander and tell him, "don't do it again." If you fail to kill Osama find the closest Taliban commander and tell him with less confidence "don't do it again" and then blow up his house on the way out so he knows you make up for your lack of confidence with pettiness.