A government whose Rule of Engagement is..."Anything goes as long as it furthers our agenda", should expect and in fact, will receive the same in return.
OBL, like so many before him, was originally groomed, trained, supported and aided by US. He was "our ally, partner and friend" against those evil communists until he got tired of being used.
As the leader of an "enemy organization" he should have been brought out alive and interrogated until he spilled all the beans.
If he was as guilty of the alleged charges against him as the government claims, then it should have been no problem to obtain a conviction. And, if found guilty; the execution should have been publicly broadcast for the whole world to see as a warning for others of his kind.