I believe it is now established that the US did not inform Pakistan prior to the raid, much less seek consent. Illegal incursion unless a case of hot pursuit. Which it wasn't.

The US claims that its information came from "enhanced interrogation" - call a spade a spade - torture. Fruit of the poisonous tree.

There was no lawful warrant for the arrest of ObL.

Therefore the US had no lawful power to seek to seize ObL at that time and in that place.

Therefore to use reasonable force to resist arrest would have been lawful.

It is clearly established by US admission that ObL was unarmed. His brave wife was I think also unarmed. Against armed soldiers their efforts could have been no more than reasonable force.

Therefore the killing was unlawful. It remains to be seen whether it was a good thing in the abstract.