I can't see why finding a terrorist who can look like a paunchy businessman would be a particular problem.

If you aren't rational within the area what yiou are trying to do, you couldn't be very effective as a terrorist. Alright, what you are doing might be raving lunacy, but that's another matter. The same applies on a much larger scale for the people who operate nuclear missile systems, they're engaged in something conpletely insane, but they have to be rational while they are doing it.