In college that could most certainly be flagged as targeting as he made forcible contact with the crown of his helmet. In this case, it would fall under Rule 9-1-3: Targeting and Making Forcible Contact With the Crown of the Helmet:

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. (Rule 9-6) (A.R. 9-1-3-I)

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