BYMONEK
Sure enough the rules apply at any airport. The difference with home base is, that you have only just met the crew. You have not experienced their level of alertness, you know zilch about them. The FOM however clearly states that you need to " ... take note of circumstances of other crew members ... " before deciding about discretion. This means you basically need to go and talk to every one and check with him/her the last few working days and level of fatigue. Furthermore you don't know the FOs aptitudes. They will be in charge when you rest, in very remote regions sometimes, and you need to be able to assess if an extension of duty can be well enough handled by them. After a couple of hours seeing them work this is certainly possible, but not at the very beginning of duty in a friggin cold and useless HQ, with barely enough time to check in and assistance from dispatch and FDM that ridicules the very term.
That's why discretion out of DXB, right at the beginning of an operation, is very different as to extending duty once launched.
The mentioned article would be very handily used by our beloved company, if you give discretion (too) early and run into even a minor screw up.
Be very careful!