I get where you are coming from but there are no clear answers. Basing penalties or suspension off of injury would be absurd. Sometimes they are just freak things and some people are made of glass while others are steel. How would you even determine injury on the spot? At that time, after watching the replay, it looked like he got shot and embellished. Many players dive as it is, you don't think they won't fake being injured to get a major call. Hockey is dangerous. You can a concussion from a high stick, from a clean hit, even a toe pick by yourself. Again, it's unfortunate he got hurt. It definitely was a 2 minute penalty that was missed. No different than the refs missing countless penalties in every other game.
When it comes to the 2 minute elbowing penalty itself. Yeah... they should take a look at that and actually remove it from the rule book. As I asked, show me an Elbow to the head that only deserves 2 minutes. To me, it doesn't get much milder than this one. If this isn't acceptable, then it should be removed and replaced with the hit to the head major that they already have.