Rotor,
Again, not a valid argument. No-one argues that airlines own the aircraft. However, it is within the right of every Captain in certain airlines to take qualified people in the jumpseat if he so desires.
We are not talking about joe public sitting down the back - we are talking about maybe your brother, your father, your mother, your sister - qualified staff passengers, who not doubt will have been approved well in advance of their flight, and who should be briefed on the what to do and what not to do while in the jumpseat.
This is a staff facility that I have been lucky enough to use for the last 15 years. My sister (a legal secretary) has twenty something transatlantic flights in the cockpit, thanks to very generous Captains who are not as closed-minded as others.
No-one has a God given right to a jumpseat, but we should all be grateful to the kind individuals who do accept staff and family in the cockpit.