Kim du Toit lists what this man did that justly allows him to be called 'our hero'.
I think one of the best definitions of that word is someone who puts their own life at risk to help others. He and another guy kept the goblin from murdering more people, at the cost of Wilson's life, and gave the police time to get on the job.
Two things. In comments to the 'Why Carry?' post, a gentleman said that you have to be realistic in assessing risks; I doubt Mr. Wilson had any idea that he would be on the scene of an attack by such a waste of oxygen, but a lot of people owe lives/health to the fact that he had a gun handy. Like I said, better to have & not need than need & not have.
Second, this was outside a courthouse; security all over. And yet it was up to a couple of citazens to prevent the goblin from killing all the people he planned on, and given a chance would have killed. As a lot of people have pointed out, the cops, no matter how good, are primarily reactive, they show up after a crime has occurred. You're the one there when it happens.
Remember Mr. Wilson, good people owe him.