You're throwing out so many hypotheticals, the argument could go any direction.
Players are in control of their bodies. JUST now, I mean minutes ago, a Line backer from the back field ran all the way to Drew Brees and took him off is feet, almost the identical line of the hit on Zach M. except the Linebacker aimed his helmet at the chest/shoulder area of Brees instead of at his face/chin.
It's best to err on the side of caution I think.
I have no idea what other HIT you're talking about. A link to the video would be good.