there were weapons in the room, osama's wife lunged at the seals and obscured the seal's view of osama, it was difficult to tell whether he was armed or not or maybe wearing a suicide vest - there was plenty of time for osama to prepare for the seals since he was on the third floor and the seals had to get past various barriers to get to the third floor and made noise doing so, not to mention the shots fired in the courtyard - finally, there has been no mention that he tried to surrender