I disagree, he two handed a player in the back of the head, driving into the ice. It was retaliation for disrupting his scoring chance. Just the fact that he could leverage his entire weight made it at least as forceful.
That it was during play might even make it worse, in no part of the NHL's cultural standard is it permissible to hit a prone player who never had the puck. It is generally understood that during after play scrums there is a level of physicality which will be tolerated.
If you want to hold that should not be the culture, I'd agree with you. And I'll grand that making comparisons like this will of course allow for different people to consider different factors as more important than others would.