Look, would a gun have saved this man's life?
Maybe, maybe not. Depends on the circumstances, and you have to factor in the dude is almost 90 damn years old. How spry the guy was will come into play. After WWII he might not have even wanted to have a gun, let alone on him at the rink.
Plus, not to disrespect a murdered vet, but he might have been a total dick head, and these kids have temper issues...
Who knows what happened, we don't even have suspects yet. Outside of commenting on the fact that gun control is stupid because senseless violence still happens, the story is just a sad happening where someone who fought for our freedom died earlier than he was supposed to.