The rule states that "No player shall target and make forcible contact against an opponent with the crown (top) of his helmet. This foul requires that there be at least one indicator of targeting (See Note 1 below). When in question, it is a foul."

Terrell Edmunds made forcible contact against the opponent with the crown of his helmet. This is a fact.

Now here's Note 1

Note 1: "Targeting" means that a player takes aim at an opponent for purposes of attacking with forcible contact that goes beyond making a legal tackle or a legal block or playing the ball. Some indicators of targeting include but are not limited to:

Launch—a player leaving his feet to attack an opponent by an upward and forward thrust of the body to make forcible contact in the head or neck area
A crouch followed by an upward and forward thrust to attack with forcible contact at the head or neck area, even though one or both feet are still on the ground
Leading with helmet, shoulder, forearm, fist, hand or elbow to attack with forcible contact at the head or neck area
Lowering the head before attacking by initiating forcible contact with the crown of the helmet

He led with the helmet to attack with forcible contact to the head. He also lowered the head before attack. You could even argue that he launched (though it really wouldn't matter if he did since he already meets two criteria for indicators of targeting and only one in required).

The other aspect of the rule is that if there is any doubt at all, you have Targeting. You can complain about the rule all you want, but it was the correct call and it's actually pretty black and white.