I'm down with people being against the vigilantism or street fight response. Trying to turn the knucklehead into a misunderstood hero who had just cause if we could only have seen a few more minutes of the back story to see that his actions are totally logical and reasonable response that leads directly to what we see is what's completely unfathomable.
Whether or not the second guy's response is truly justified and ok is totally debatable. Whether or not the guy that got knocked out was being a total ***hat is not.