You would be right.
The operative word that you selected is "Arrogant",
Arrogance affects everything about the person who bathes in it, including their decisions regarding their responsibility toward others, including dogs.
Like I said, The entire problem here is Angie Harmon.
I will not dispute that she seems to be part of the problem, but I don't think she was all of the problem. I think a guy carrying a gun and using it to shoot a mid sized dog under these circumstances may also very well be part of the problem.
His actions seem disproportionate to the threat he allegedly faced.