You're assuming the property owner was sane, by the sounds of this story he doesn't sound to be. He seems like an old paranoid racist that saw a Hispanic looking man in his driveway and immediately assumed he was going to get robbed. Sure, that's just me speculating but that's the impression I got from this story.
It isn't fair to assume a person is an insane racist regardless of the circumstances before any of the case is fleshed out. He may very well be, but the truth is that the vast majority of people are not, in fact, home invasions are more common than people who fire on others without provocation.
I tend to think that the fact that the media makes it a priority to point out the race of either party points toward their racism more than that of the subjects. Race doesn't come into the equation when you, your family, or your property is at stake.
I don't personally think he should have fired on them, but I hold judgement until more details and his personal testimony come out, there are always at least two sides to a story, and it's obvious the news media isn't privy to either one at this point. I would have waited for them to enter the home, but some people don't feel that way. All I'm saying is don't judge too soon. If it comes out that he was basing his decision on anything other than self defense and the defense of his family, then judge away. I understand the passion involved in these types of cases, but it serves no one to let passion rule over thought.