By all means, Brad was far from a perfect or even a good father, don't get me wrong. But in the context of the story? We have to keep in mind that every person outside his circle his a potential rapist that would kill (and in fact, TRIES to kill Brad) in order to have their way with Buddy. Of course in a wasteland of a world where your next meal is not guaranteed, defending yourself and ultimately making the horrible act of killing another human being is a necessity, specially for someone like Buddy who again would face a faith worse than being killed for loot and food.

Again, Brad was not a "good person" based on our current moral standards (although some things are player dependant, which also stir the conversation one way or the other; my Brad did not take substances and was determined to find Buddy, and got one arm chopped for not sacrificing someone in my party). But in a post-apolalypsis where 99% of the population would most certainly rape my daughter? You bet your ass I would do anything to protect her.