You have a good point. It is also can just be fun to discuss finer points of laws that we care about. The problem is that the correct answer to a lot of situations is "it depends". Real life is fluid and factors are constantly changing. I have seen scenarios where someone has a clear justification for deadly force one minute but not two minutes later when they actually decide to shoot.
Here's my plan. If there is any way to get out of a situation without significant harm to myself or my family (my dog is part of my family) without using deadly force, that is the path I will choose. If that means I need to retreat from a dog / human / whatever, or "lose face" by apologizing when I have done no wrong, so be it. But if there is no other alternative available and I am forced to use deadly force, I pray that I will not hesitate in doing so. If that ever comes to pass, I will gladly face any legal consequences knowing in my heart that the alternative was far worse than anything man's judgment could impose.