As far as the rules are concerned, yeah, more or less. And really there's no way to penalize/suspend for that kind of hit unless you're okay with eliminating virtually all body checking in the NHL. The head is going to be contacted on virtually any hit where one player is lower than the other, whether because of skating stride or physical differences in size. It's shitty that Eller got so fucked up, but the hit was clean. There was no elbow, no jump, he was "eligible" for a hit as he had the puck (if only briefly), and both players' torso/hip area clearly contacted first. The only problem is that the hit was somewhat glancing so instead of the two players' torsos/hips taking most of the impact and bouncing off each other, Gryba continued past him and clipped his head, stunning him, sending him flying and resulting in his face hitting the ice. Gryba did everything right there, but the point of contact was a few inches off center, and that's the end result.
Why do you hate freedom?