From what I understand, he didn't hit anyone but the thieves. There were items missing from his neighbor's house, which should fall under "unlawful interference constitutes attempted or consummated theft," it doesn't say you can't shoot them while they're running. In fact, if it was his personal property he'd clearly be justified if he "reasonably believed there was no other way to reacquire his stolen property" (or something like that). I'd like the protection of a third party's property to be seen in that same light.
On top of it all, the guy's 64. He's fighting crime in defense of his fellow Americans and their stuff. He should be given an award, not jailed. I know it'd be an honor to have him as my neighbor.
Maybe I'm just upset because with every story like this I'm less and less likely to stick my neck out for anyone but me and my immediate family.