Principles, or a Convenience?

I recently saw a person publicly declare he is rejecting the Zero Aggression Principle (ZAP) after years of following it. The reason: Someone had insulted his girlfriend and he decided that the ZAP was inconvenient and “pacifist” because it informed him that using violence against the insulter would be something he didn’t have a right to do. He didn’t like this and started posting links claiming that words cause real harm.