Terrorism, as a strategy, acknowledges the weakness of your team as compared to a much more powerful enemy, and thus seeks ways to commit acts that get "magnified" by popular response. The success of 9/11 wasn't the death of 3000 people, it was the advertising that the event garnered, the fear that it instilled, and the reaction that it inspired in the enemy, which proceeded to launch a couple of extremely costly wars which wrought more destruction on the country than the terrorists could ever dream of being able to commit on their own.
Captain Underpants's mission was a success from the moment he made it past security. It wasn't the home run he would have liked, but just getting onto the plane was enough to launch a renewed effort towards costly and unpleasant security measures, get the entire country squawking at each other again, get people shouting for security over privacy, and security over personal rights and the rule of law, and once again make people afraid to fly.
We have a ridiculous "nobody must ever die" attitude here, even though we live in a country where 7000 people die every day, many of whom had their lives cut short as a result of lifestyle choices they made. Every day 300 Americans die in accidents of various kinds, such as car crashes, falls, etc. Every day 50 Americans are murdered. But a failed attempt to set a fire in a plane with 300 passengers, in what was probably the most successful attempt against an American flight in 8 years, this gets us in a tizzy. It disturbs our fantasy that life is without risk.
-harry