While I see your point, we have no idea if the young people affected were trying to "get involved." According to the story, the man came towards them and engaged them. Sure, they could have stayed sitting and ignored him, but the one who stood up, how could he have ever predicted he'd be shot down? And there are certain situations where people should step in and not turn a blind eye. There is no big "lesson" here, just a very sad loss of life and still a big question mark of what we can do to prevent these situations.