Michael Bernstein: "The thinking goes like this: If all non-terrorists obey the 'no-fly-zone', then obviously anyone violating it is a terrorist and can be shot down with impunity. Ergo, an increase in security."

Right, because it has been the U.S. policy to shoot down airplanes with impunity if they violate a domestic no-fly-zone.

What a plane violating a no-fly-zone does get is a helluva lot of extra attention. By limiting the number of airplanes over a potential target like Disney, you reduce the number of planes where you have to wonder "gee, has that one been hijacked by terrorists."