This isn't justice. When did our society lose the concept of justice? Vengeance is not justice.
I can understand the desire this man had to kill the man who killed his children. I can understand the anger and pain that would drive someone to do this. But it's not justice.
I re-read the entire thread, and saw no mention of anybody thinking this was justice. In my mind, there was no thinking. His children were slaughtered, and he returned fire. I would not be able to enter a guilty vote.