There is one small point worth adding to this discussion, as I haven't seen it mentioned yet: an important logical fallacy in the retired Navy Chief's "method". It's subtle, but pervasive, and here it is: the "method" purposefully confuses concepts of defense and retaliation. Ignoring obvious situational problems already mentioned (the activist could leave, call out to his friends, or get the cops), the "method" suggests that defense=offense. While there can be much truth to this statement, it ignores a problem with the sequence of events in both the "method" and the WTC attacks.
We cannot protect ourselves from the WTC tragedy, because it already happened. The activist is right: punching the Navy Chief back after being struck the first time solves nothing. However, the activist is a very stupidly written character (a sign of the Navy Chief's weak argument), and in reality should simply leave. Striking the Navy Chief would, in no way, protect the activist from being punched the first time. However, if he's a clever activist and truly understands the differences between defense and retaliation (and doesn't feel like leaving at this point), he'll agree that non-violence is the best way, but strike first and faster the next time the Navy Chief tries any funny stuff. This is defense. Protecting oneself offensively prior to a known impending attack is a very valid defense, should it become impossible to escape. Avoiding retired Navy Chiefs like the plague is an even more valid defense.
When a person attacks you, they are at their most vulnerable. After the attack, they are quite ready for whatever response you prepare. Osama bin Laden is trying to draw us into a carefully constructed narrative in which the U.S. will play the role of the Great Demon, the villain that the Jyhad must destroy. He is at his most protected now. He is quite safe.
The WTC tragedy has more to do with airport security than radical religious aggression, because radical religious aggression will always exist. You can hunt down one terrorist, but the truth is that you solve no problems. If you bomb the country the terrorist is hiding in, you create many new problems.
In fact, radical religious aggression will grow if we ever succeed in killing bin Laden. From this, we can see how clearly defense does not always equal offense. It may often be an important tactic in personal scenarios (second only to running or getting the police), as a means to avoid harm if one is cornered and no other options are possible. However, this is not a safe metaphor when applied to nations. We cannot see the world's nations as a group of people who occasionally scuffle. We can conceivably protect ourselves from future attacks, but the way to do this is the core of the debate. Retaliation can never protect us from previous harm, only lowers us to the level of the attacker.
The "method" recognizes only one solution, but the skill is all in the framing of the scenario so that the listener ignores all the obvious options. By calling an attack on Afghanistan a defensive measure, we lie. It is a retaliation fueled by desire of vengeance. Now, I'm not here to debate the morality of vengeance: let's just call a pig a pig. If we argue for vengeance by calling it defense, we are not.