He was unarmed.  And now it looks as if he was captured before he was killed. His body was disposed of post haste, such that it could not be exhumed.  What would a post-mortem have revealed about the manner of his death?

Of course I don't know about the manner of Osama's death, but I do know that the USA was involved in the practice of moving prisoners to countries where they would be tortured. I do know that the USA still has many prisoners locked up in Guantanamo without even the prospect of a trial. I do know that the Americans invaded Iraq on the basis of there being 'incontrovertible evidence' of weapons of mass destruction.  So I know that we are dealing with a country which has been untruthful in the past about many connected things.

I would not be surprised to find that there never was a global organisation called Al Quaeda, but rather a number of disparate groups who appropriated the name to make them sound more dangerous, and in doing so, played into the hands of the politicians in the USA who used the name to convince the voters that they were protecting the world from a massive Islamic threat, while really making sure that they held strategic military positions when the global fight for oil and gas hots up.