The case 3bo0od07 makes for why George would have disappeared if he were still alive is a bit of a stretch, but then again, isn't everything on Grey's? "George went to Iraq without saying a word," 3bo0od07 proposes. He then decides not to reveal that he's alive so that when he returns to war, "his family and friends won't be in grief all over again." That's a lot, but, hey, anything can happen.