In my eyes that was clean. Shoulder down, elbow down, and he explodes into the hit. The guy simply had his head down. The one before this on the panthers player was bad due to the straight intentional head shot. Also, the puck had left the players stick a few seconds prior.
I play hockey and had something similar happen to me once. It was a clean play I was just leaning the wrong way and got caught in the face. Luckily I wear a full face mask and it didn't hurt much but it sure as hell didn't feel good. I probably would've been knocked the hell out if I wasn't wearing full face coverage though.

