I'm thinking they can becuase the PWA allows it, so don't worry about it.

Maybe they dropped some other rotations on their scheudle and now need to pick up some WS to get back to GS trigger. Maybe this notional WS is a broken up trip that starts and/or ends allowing a commuter to drive to the DH airport and fly the trip.

Maybe there is a boat-load of credit built into this notional WS.

And as Fangs said, my WS pays me more than your GS pays me.