Unless OBL wasn’t killed, or some other aspect of their mission could’ve been embarrassing to BHO.
OBL was already dirt along time ago. It was better to just leave him lie or the WOT and mission in the Mid-East would have been hard to keep going because Liberals would have said it was over. The Libs that came to power after Bush wanted to end Afghanistan, Iraq, and the War On Terror. They thought they could put people at ease and accept the end of the WOT by getting Bin Laden, or convincing everyone they did. They thought it would bring closure, but of course it did not since the movement is much much bigger than one man. But, Bin was gone well before Bush was out of office.