Yeah. Kinda a freak accident. Don't think a cage or a more sturdy helmet would have helped at all. (unless is was like those new MLB helmets that no one wears)
IMHO, these things happen, but the chances of it are still pretty rare. It's like when Pronger's heart skipped a beat when he got hit in the chest with the puck, or when Malarchuk got his throat cut. Possible, but considering how much hockey is played, very very rare occurrences.
Concussions are still the bigger problem with helmet protection...by a large margin.