What about the scenario in which a person sees a child being sexually assaulted and intervenes? This is certainly not self-interest on the part of the rescuer,

What about the scenario in which a person sees a child being sexually assaulted and intervenes? This is certainly not self-interest on the part of the rescuer, other than satisfying a deeply-held moral conviction. It may also be well thought-out. For example, my children have never been raped but I know I would use lethal force if necessary to prevent it. Even violence based on self-interest is ultimately grounded in morality. For example, if one has a right to life, self-defense is morally justified and murder is wrong. Both are motivated by self-interest (one licit, the other illicit). If violence does not contain some moral component, then we're stuck with very bizarre consequences (e.g., genocide and violently stopping genocide are on equally amoral footing).