But he had already gotten off the airplane, and it's a lot easier to cause damage with a single bullet on an airplane than it is to cause damage with a single b

But he had already gotten off the airplane, and it's a lot easier to cause damage with a single bullet on an airplane than it is to cause damage with a single bullet while leaving an airport - so either he's so stupid that he'll carry the bullet onto every airplane, waiting for the chance, or he just forgot that he was carrying it, as he said.