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.
No.
I have witnessed people dying from a dog merely jumping on them.
No one invited onto private property is required to risk his life over the irresponsibility of the property owner.