“The dog could not have been THAT viscious if he chased it out of the yard.”
The level of viciousness cannot be determined based on the distance and direction traveled by an irrational creature. Dogs pounce and then retreat all the time. And they continue to run when they start running.
Incapacitating the dog might have been necessary, because it might have turned back and attacked the guy.
People who make comments like that need to be on leashes -- very short leashes.
This remark is bizarre. You speak of "irrational" and potentially vicious creature and then state that they flee and continue to do so. That sounds predictable to me, if not rational.
Here's an analogy to the situation: if a bad guy comes in your house and you shoot him, no problem. But if he's on the other side of the threshold and you shoot him in the back, you go to jail.
He shot the dog on his neighbor's property. He can provide no evidence that it threatened him, has no witnesses to verify his claims, discharged a firearm in the proximity of other houses, and intended to destroy a neighbors pet.