Most of Emirates' foreign workforce originates from the world's largest kleptocracy, a society which is fundamentally and irretrievably corrupt at every level, from tea-stall owner to the highest court in the land. The reason your jumpseat pass is "fully ticketed" is because your management quite rightly assumes that if it was "captain's authority" to give out the jumpseat many of them would be selling that seat as a nice little earner.
The company will never, ever under any circumstances give the captain the chance to make money off the jumpseat. Ergo, you as the passenger will always pay for the privilege.