The problem with that theory is just how ridiculously fragile such a secret would have been. All it would've taken is 1 person not friendly with Al Qaeda/Taliban to have learned the truth and to have informed the US about his location. Hell no-one would've even had to know that Pakistan was involved just to avoid reprisals.
The whole buried at sea thing though... honestly its a lose-lose situation. They disrespect there traditions by burying him at sea (though frankly he's not shown himself to be deserving of any of them in the first place) and Al Qaeda start a **** storm over it. They bury him ANYWHERE and his gravesite becomes a shrine to the fundamentalists and they still start a **** storm because he's dead. Honestly though it makes no difference, they will react at his death anyway, all it will change is HOW they react.