In To Kill a Mockingbird, why does Heck Tate not want to shoot Tim Johnson?

Tim Johnson, of course, is not a man but a dog, and Heck Tate
wants him shot because he has rabies and is foaming at the mouth. Rabid dogs can be dangerous,
because they act irrationally and have been known to attack without cause. Since Tim is weaving
down a neigborhood street, he poses a danger to others, and everyone is ordered inside. Heck
doesn't want to shoot him because he apparently is not a crack shot, like his friend, Atticus.
So, Heck decides to turn his rifle over to Atticus, who he remembers as being the best shot in
the county. Heck knows that in spite of Atticus' long absence from shooting a firearm (which he
does not even own), "One-Shot" Finch is still the best man for the job.