Departing MMUN-for LSZH i don't think cpt could have uplifted much more then 2,5T on top of fltplan with a full house (MTOW B767 out of MMUN).
Crew not necessarily arrived below min diversion fuel at dest, just maybe waited a liitle bit too long before going to altn after first GA. Did ATC advise crews no upgrade cat3B anymore expected for any rwy?
Zurich apt authority involved definitely:2 backup pwr failures at the same time?? It's like winning the lotery!
Final reserve 767 around 2T.