I'm going to disagree on whether the hit on the LSU QB should have been targeting, and not because I'm a Bama fan. Over & over I hear fans calling for targeting or holding in situations where they don't actually understand the definition and the rules regarding either. This is one of them. Helmet to helmet contact, in of itself, is not targeting. Although there are some nuances and context, the short version is there has to be use of the crown of the helmet and an intent to target (or no effort to avoid) a vulnerable area (especially the head and neck). Here, the Bama player is making a normal tackle that results in helmet-to-helmet contact (not a violation), doesn't use his helmet as a weapon, and it's the facemask and forehead area of his helmet that hits the LSU QB, not the crown of his helmet.
Basically, he makes a normal upper body to upper body hit and the facemask and forehead of his helmet hit the chin and facemask area of the guy he tackles. That doesn't come close to meeting the standard for targeting and is why the refs nor the review officials called it. It was a hard hit, was a bit late after the throw, he did put a little extra effort into driving him into the ground, and it definitely deserved the roughing the passer flag, but if you know the definition of targeting and the rules regarding it, the refs 100% got it right.