I like the rule, just not how its being applied. I believe it was right for the ref to throw the flag in this case, but review should have overturned it. Shoulder to the chestplate is a good hit. Any other contact was incidental. If the intent is for the offensive player's head never to be moved by a tackle then all tackles will have to be below the waist...
The part that upholds it for me is this part of the rule: The head rocks back before the contact to the chest, which was initiated by his helmet. The hit, to me, would be a good clean hit. However, in the bounds of the rule as written, was upheld for this reason. The defenseless player is a judgment call, which in this case can arguably fit.
I like players being protected, and I agree that something needed to be done to stop the "head hunting" Sports Center type of hits that the defense loved to deliver to intimidate the offense from coming over the middle. And I like that there is replay review of the hits, I just sometimes am amazed that replay guys seem reluctant to overturn what seems to be obvious. I think that Tenn kid made a hard hit and a legal hit. I agree with Scott that the ref should have thrown the flag, he saw it bang/bang. But the replay guy gets to see it in slow mo from angles. He should have over turned it. I thought in both the hits I saw this weekend they were right to throw the flag and that replay should have over turned both calls. BTW they still miss a bunch of head/head contact but realistically they can't get them all, and I think in many cases the ejection and if it's in the 2nd half having it carry over to the next game should be reserved for only the most egregious calls.