In Maine, at least, I was taught that you are legally allowed to use lethal force to protect your property, but NOT anyone else's. That certainly doesn't mean you should, and I didn't intend for my post to suggest that he should have shot the man.
If he had been caught breaking into that man's house, who's to say what his intentions were? You wouldn't know whether or not he was there to rob you, or kill you. I do disagree with NC-Heel about verbal warnings. I wouldn't just open fire on anyone breaking into my house, without first giving them a chance to surrender. I hope to god I never have to use any of my firearms in a lethal manner. I say if you're at a safe distance from the perp, then let me know you're armed and to eff off.