In my opinion, he over-reacted and should not have used his gun. But I would think that a good lawyer may be able to turn this around for him. The castle doctrine applies to businesses. If the cops can't proof that he shot outside his business (and remember: its not that he has to proof that he didn't... the cops have to prove that he did), he may get away clean. But chances are not good for him. Kind of all would come down to a good lawyer and the right jury. Unless he is super lucky and hits a prosecutor who isn't interested in following up on this.