Seems to me that that would be exactly backwards. The centrifugal force should be pushing folks away from the planet, and stopping the spinning would cause folks to be pushed more firmly to the ground, not loosen them from it. (Get a ferric metal ball. Put weak magnets on it. If you spin it fast enough, the magnets will fly off. If you are spinning it and the magnets are affixed, stopping the spin won't cause the magnets to fly off in all directions, although inertia may cause them to slip).