For those rejecting the requirement of a nexus netween location of a combatant and the lawfulness of the target: when do US personnel become a lawful target?

Is the President a lawful target despite the fact that he is not in a combat zone? He does direct the war effort, right? What about Joe Schmoe back on the block? Is he a lawful target while he's chillin' in front of his TV? If not, how do you distinguish the lawfulness of targetting bin Laden while he is off the battlefield?

stirring the pot...