I am not saying he was armed. I am saying they killed him on sight because there was the possibility he was armed.
You don't shoot somebody that you should arrest by the pure possibility that he was armed. Just like you don't shoot hostages, because there could be a small chance that they cooperate with their kidnappers.
Also for an intentional head shot, you need to aim pretty carefully at your target, long enough time to know the intents and possibilities of your target.
No matter how fast they did it, he would have had time to throw on a simple suicide vest. A few sticks of dynamite, a few blasting caps, a HV battery, and a momentary switch. Nothing fancy. He could have had it rolled up under his bed and and armed it in about a minute. I doubt he had one. From what I have seen he was not living in a constant state of emergency, but the SEAL team did not know that.
Such vests are only build by amateurs. And as you can often see, they are not good - suicide bombers survive with them. You also don't build such a vest once and then store it under your bed for
five years in anticipation of the USA to come and get you. Dynamite is already useless and dangerous after much less time, stable explosives are expensive and not easily detonated.
Also, why should he have such a vest? If you want to take the whole bloody world with you, you would have AP mines in cabinets. You could store enough explosives to down the complete house. Arming them would require some work, but by the time the helicopters are heard and the first soldiers rope down into your house, you would have done that and already hold a deadman switch in your hand. Shooting him then would be especially stupid. There could have been enough explosives for bringing down the helicopters as well in the house, if Osama really prepared for taking any attackers to hell with him.
Remember: Bin Laden wasn't crazy. He had a very radical view of the world and strong hatred of the USA, but he was not crazy. Not in the sense of risking premature explosions. he would have worn a ballistic vest, maybe even in his sleep. He would have armed bodyguards around him. He might not have been afraid to die, but all that we know speaks of somebody who did not plan to die. You don't go hiding in Pakistan and develop secure communications channels for you, if you plan to die in battle soon. You do that for staying in the game when somebody hunts you. Bin Laden did not wait for the USA to come, hiding in a hole. He had a small relatively secure exile. Actually he was even far away from the battlefield, where drones did not seek him. Would you say that this speaks of a crazy person? That had a wish to die?
Sure not.
That speaks of somebody who wanted to stay in command regardless how hard you make that.
---------- Post added at 07:57 PM ---------- Previous post was at 06:53 PM ----------
As additional information about Bin Ladens plans: he had $500 and two phone numbers sewn into his clothes when he was killed. That is something that you do if you plan to escape with nothing but your bare clothes on, and can't rely on banks to get money after the escape.