Well, the answer on the FSW is the following:
(i know we should not publish internas. But this is discussed ad infinitum and basically it's a procedure and no names are involved. To clarify what is out there, and this is a matter of safety, i only copy the answer)
"The flight can be operated within a variation of the flight time limitation using a two man crew only. The third crew member on these night turn-around operations have been added after consideration by the XXX, to improve operating crew member alertness through in-flight relief. They have not been added to extend the flight time limitations and if captain’s discretion to extend the flight duty period for 2 man crew has been used, it must be reported."
The way i interpret it, is that the flights "can" be operated with a variation.