If you do this you fit the profile of a terrorist a little too closely. Assuming that someone wanted to stick around to bomb another day they would do just what you proposed and have their bag with bomb go off on the plane that they were not on. They do head counts on the plane, and if you don't show up they have to account for you. This could mean anything from calling your number and verifying you weren't on the plane to deplaning everyone and rechecking all the luggage. Its an irresponsible stunt just to try to get some extra miles, IMHO.