He would have been in even less trouble had he simply called the police and let them handle it. Although we don't know all the facts from a simple news story, there is no indication that the man's life was in danger, nor the lives of anyone else for that matter.
Self-defense is one thing, shooting into the ground to stop a suspected robbery (in his mind) in a house that you don't even live in is quite another.
If a state has laws which can lead to a person's arrest for shooting an intruder he caught trying to break into his house, how much more would those same laws come back to haunt someone used a weapon to defend a home in which he didn't even reside?
I know I won't hold the popular opinion on this one, but shooting into he ground to scare the crap out of someone who showing no indication of harming you or anyone else is not the smartest of moves. I could see justification in the act if the guy was breaking into my own home and I shot him in the nostrils, but shooting into the ground to stop a robbery of someone else's house would go beyond my standards for a self-defense justification.
In fact, the guy would not have been in any trouble had he simply called 911 and allowed the police to handle the matter.
I'm certain the fellow was well-meaning in his intentions, but he had no way of knowing if the burglar had a gun or not.
To intervene over someone else's stereo or boom box, or any other household "stuff", and run the risk of getting shot and killed by some crystal meth-head out scoring some loot for his next fix, was an ill-advised move.
Lastly, he really had no right to intervene. Just because he owns a firearm doesn't qualify him to assume the duties of a law enforcement officer.
Now the poor fellow is in deep trouble, having to go through the unnecessary stress of being arrested and handcuffed and carted off to jail. He is out the expense of an legal counsel and has had all his firearms confiscated.
