Another point about discretion ex DXB - why? There "should be" enough reserve coverage to make the flight legal under FDL's being home base to everyone.
Which brings me to my next point. When the decision has been made to operate into "captains discretion", then the FDL's, although offering guidance for using discretion, are being breached. Therefor any extension of FDL's is beyond the company's accepted and regulated limit and now any recourse is null and void. In other words, the skipper is wholly responsible for any stuff-up by anyone on that flight whilst on duty.
"This incident, your Honor, may have been avoided if the captain had maintained and had kept within the legal limits of the established FDL's. It seems also, your Honor, that he did not follow the company's requirement to understand each and every crew members circumstances prior to ignoring the regulated FDL's"
Some may argue that's normal, but that's another issue.
halas