Hmm...the guy needs to get a lawyer. I can't tell from the story whether the drone operator was taking pictures of this guys house or a different guys house. If the drone was above the shooters house then what is unlawful about shooting down a drone? You don't know who is operating it or what it's doing. And where is the law saying you can't shoot a drone? It's not alive. And apparently it's not illegal to discharge a gun here for a lawful purpose.
>> Possession of a Weapon for an Unlawful Purpose
Possession for unlawful purpose... huh?
>> Criminal Mischief
Seems to me the mischief was on the part of the neighbor, and it may have been criminal (was he spying with a camera?)
You could say the same about an airplane or a helicopter. What's the difference? There should maybe be a minimum altitude to fly over other people's property, but in the age of Google Earth, people can look down on your yard if they want to.