Consussion. You can tell instantly when they go to the zombie arm thing. Not an illegal hit by any stretch. Rice was going head first at an awkward angle leaving nothing available to hit but his head, and the defense CLEARLY went shoulder first instead of head first. There was no intent whatsoever. Just one of those freak plays that happens from time to time in the game of football. There will never be a rule that would have protected Rice in that situation.
I agree on the rule part, but Seahaws ahve been fined for far less.