It takes nothing to shoot down choppers. If they knew about the operation and wanted to protect bin Laden at all costs, there is nothing we could have done to prevent the entire SEAL team from being taken prisoner or killed. Note that the Taliban have taken down 2 SEAL choppers using RPG's. The Pakistanis not only have MANPADS, they have SAM batteries.
And then we would have sent in missiles/bombers and Pakistan would have lost its deniability.