[shrike6]

The question makes me think about the movie "By Dawn's Early Light". Where President Martin Landau is trying to convince various government and military officials that he's not dead and is actually the President. Now given the situation you are giving is no where near as dire as that movie but the SOD would have to be able to prove who he was and also more than likely what he was doing between the Thanksgiviing Day massacre and when he reappears as well. Plus theres the constitutional questions surrounding this event that a Supreme Court would have to decide not just the validity of Civgov but also what kind of time limit is there on line of succession if there is one. I don't believe it is actually spelled out. This is a big can of worms you opened and intriguing to think about.