A PERFECT example of a rule written with no effective way to enforce. If the defender goes in lower (roughing for low hit on the QB). If he goes in higher he risks helmet to helmet contact (roughing the passer - targeting). This was a picture perfect tackle with no intent to injure, no rule violation and no where to fall except down. He was basically flagged for not falling up and even Aggies can't do that.
Referees make this call because they are SCARED not to. They know that they will not get into trouble for making this call but they might be for not making it. Rules should not be written that cannot be supported by good game principles and technique. If this is a penalty in someone's opinion, I would like them to explain how the tackler should have made this play.
Let's give the QB flags or a different color shirt like they use in scrimmages. Two hand touch and he is down.