Really? I'd have thought dozens - if not hundreds - of JS bookings on any given day were backup or contingency plans.

If anyone wants to crack down on a holery, let's require the FAA to announce their intent to occupy the jumpseat with some sort of notice. An AA JS rider on one of our flights recently missed commuter flight B on SWA because the flight A jumpseat on us was looking good...right up until the FAA took it 15 minutes prior. That FAA dude had been sitting there over an hour but didn't tell anyone what he was going to do, and must have known his own intentions an hour before that. Had he done so with more notice, our AA friend could have gone elsewhere. Instead, he missed both and waited several hours to try again.