He was a "creature of American foreign policy," as Butler Shaffer describes him. Killing him Mafia-style and feeding his carcass to the fishes eliminates any possibility of a singing canary.
What about the various reports years ago claiming bin Laden had died of natural causes? Well, no one remembers those anymore, and besides, the Taliban has confirmed his most recent death. But what does that mean? If OBL is in fact still alive, he could very well prefer letting the world believe he's dead.
But what if Vito Obama really did make the hit on a real, live bin Laden? Why would the U.S. want to kill the man who's been the excuse for fattening the MIC? In a word, ratings. And besides, the MIC doesn't need OBL anymore.