In both the airlines I have worked for positioning staff are/were booked seats in the highest class cabin available... most sensible airlines operate this policy, and block off the seats, thus removing them from the system. If only jumpseats are available it is ok to ask the positioning crew if they would sit there, but under no circumstances do they have to.
Personally... it depends... before a long sector, there is no way I am losing the relative relaxation of the cabin, as you cannot relax on a jumpseat and the involuntary involvement in the flight adds to the duty. Afterwards.. well, almost certainly yes. But it is my choice.
Captain X has been shafted by a management who cannot see beyond an artificial bottom line... I sense a hidden agenda.
Alien