That was a blatant hit in my opinion.
Tell tale signs of a former football player ....
The ref stepped waaaay out his way from the pack of players to be directly in line with the QB, dipped his shoulder, lunged forward on his legs long before impact and threw his forearm forward to boot.
Classic blocking technique designed to merely break up a play.
NOT a typical "protecting yourself" scenario.
Watch the refs feet.
Methodical movements.
Look at how much space is around the QB once he comes out from behind the pack.
Absolutely no reason for the ref to move over
that far and be where he was.
The ref clearly has his eyes on the QB the entire time.
Possibly just a der der der moment ... who knows exactly why it happened.
Maybe he missed playing and had a flashback and thought he was in the game. 
Put me in coach!