OB, another perspective on why the hands slow is that, during the release, when the left wrist is going from cocked to uncocked, there is great centrifugal force acting on the hands. The direction of this force is inline with the clubshaft and directed towards the clubhead. When the left arm is like this | , and the shaft is like this / , there is a component of this centrifugal force pointed at the ground, and another pointed away from your target. It's this latter component of centrifugal force that slows your hands as they pass from the right hip across your body toward the left hip.
During this brief interval of release, if, as Yoda suggests, you continue to apply lag pressure, you will continue to do work on the primary lever assembly, thereby increasing its angular momentum. The hands will still slow down, but the work done against this slowing force will result in greater clubhead speed at impact.
Threaded Mode