I don't think it's the same as shooting a trespasser, the theory for shooting trespassers is that they may directly pose a threat to your safety. It's hard to argue that a drone poses such a threat unless they're chasing you or have a weapon mounted on them or something.

If the shooter from OP's link used a .22 or anything other than bird shot, then they are a real fool and a danger to everyone around them. Off the top of my head I'm inclined to think that the reach of a shotgun is probably about the right distance that ought to be protected, maybe a little bit further because of cheap optics.