Nick: If a player is not "at his seat" by the time the last down card has been dealt, I will always kill that hand. At the same time, if a player is not at his seat when it is his/her turn to act, I will always kill that hand. It matters not one speck to me whether that player is "all-in" or not, nor does it matter if that player is the big blind.
If you are not at your seat when it is your turn to act, your hand is dead. I have no patience for players who stall or otherwise hold up the game. Especially in a tournament, where other tables keep going and one table is not getting as many hands in play because of some yo-yo's antics.
Chet