They've had the hands to the quarterback head rule for a few years and it's a bit ridiculous when you consider defenders raise their hands to block a pass. But if they're going to call it, they should have called it 2 plays earlier when another defender hit Manning in the head. I said that to my brother when it happened and he didn't believe me. 2 plays later they call it on a critical play in the game.
I think the other call was explained as a defenseless receiver because he was already engaged with a defender. It was tough hit, but once again that defender went at him head first and that's what the NFL needs to get rid of. It appears that over the years that defenders forgot how to tackle and now just resort to the spearing dive at the runner tackle. Too many players are getting hurt to allow that to continue. But that game was ugly with too many lame penalties called on both sides.