Have you ever been robbed before? In your own house? Maybe while you were sleeping? Your property, your rules. I am sure many in the guy's situation could have also lost it and delivered instant and hard justice on the spot.
I don't disagree, a guy broke into my condo once and I came home to find him stealing shit, so I knocked him out, and would do it again if someone broke in or attacked me again. But I didn't chase him anywhere, or use an object to attack him, and felt like I was in reasonable danger at the time, I thought it was justified and not out of proportion. At the same time, the charges against him are also justifiable