If the defender tries to swat down the ball and slaps the top of the helmet that should not be a penalty.

The biggest change in that rule I would like to see is less protection for a running QB than a stationary QB. If you are trying to evade the defender you should get less protection than if are standing on your back foot trying to throw. You can not protect your self while throwing but you can while evading. That means if you duck your head and there is helmet to helmet contact then no penalty.