I've heard the phone call on the radio, the guy is nuts. He should be locked up for psychological reasons. Still, the act itself was not wrong. he was protecting his neighbors property when he shot the two people who were carrying things out.
911 dispatchers and police officers are not lawyers, judges, or jurors. They provide a valuable service but judging, punishing, advising, counseling, and interpreting laws and norms are not part of their jobs.
He gave warning (not even a requirement). The police still hadn't been there after 8 minutes from the time the call originated. Where were the police? How long after he hung did the police show up?
You shouldn't be outraged over the crazy guy, you should be outraged that the wealthiest nation in the world can't provide adequate police service, that all the wealth of its people is being blown on wars, weapons, and aide abroad instead of providing services for the taxpayers.