Yea maybe to some degree their hands are tied, although I think there is still a lot more they could do to protect players. As you say, match penalty is an auto suspension, or straight up if you seriously injure someone that's an automatic suspension (and one that's actually punitive, rather than giving the appearance of punishment), unless it was a clear freak accident. If you give the players an incentive to actively avoid injuring each other, whether accidentally or not, the game will be much safer. At this point, I don't think the NHL is ready to take things that far, because fans love the violent aspect of the game.
The hitting (violence) isn't the problem. In this case, it was hitting a vulnerable person who had lost control. Only crap people condone that.
In reality I can't fault the NHL too much, because I think the integrity of most leagues is in serious question for one reason or another. I just wish, at some point in my lifetime, I'd see people put doing the right thing over profit.
It isn't quite that simple. The NHL for a while tried to cut back on the fighting, but hockey is an odd bird sport, and fighting is kind of a pressure release mechanism, that prevents wickedly cruel things from occurring.
What I find hilarious is that for the longest time, people complained about violence in hockey (and we are talking after the time when bench clearings were banned), yet violence in baseball (throwing a ball at 100 mph at someone's head!) is almost encouraged. Bench clearings happen quite often in baseball (relatively speaking), yet nothing. NASCAR celebrates crashes
and driver to drive conflict, yet nothing.
But allow checking a sport or fighting, and it is barbarism.