He has convincing power, Right or wrong but he stands by what he says and always keeps the same stance..
In my opinion though, ISI and US must have worked together to root out Osama, but to avoid Alqaeda Wrath on Pakistan, Pakistan would have asked US to stage this drama of saying that they didn't tell Pakistanis about the Raid, So to the Alqaeda the message would go that It was only US that Killed Osama and it gave Pakistan the benefit of doubt and probably will keep Aqaeda always in confusion whether to think Pakistan as an Enemy or a friend. So they(Alqaeda) will never friendly contact Pakistan nor attack Pakistan because of the Confusion... US says they burried Osama in Arabian see. It is a long route from Pakistan to the Arabian see and there is no way they could have carried him in Helicopters without being intercepted by the Pakistan Air Force. 2ndly it is said that Pakistani Army was only few blocks away from the compound yet the US raid happened for more than 40 minutes and no one from the Pakistani Army came to intercept the US...
There is also a possiblity that Osama was already dead but for political reasons Obama would have asked Pakistan to help them in this drama so that it could boost the morale of the US Army also restoring their honor because if they had announced that Osama has died of natural causes then it would have made the world laugh over the Super Power who couldn't manage to do the job despite so many resources. Such Drama was also aimed at decreasing the morale of the fighters who were fighting Against US in Afghanistan..