Flyingcroc???? Where did unforeseen weather conditions arise in this case?
They had normal cat3 wx conditions with 2 operative independent separate...cat3B rwys when they first arrived at dest. So they went to make a cat3B app and land, end of story! They probably had more then MDF when they first arrived at dest! Then when they had started their first approach problems started. Analyse succession of events in time in this case. Your statement they should have diverted before arriving at dest because wx was cat3B doesn't make sense.
(And 2,5T fuel on top of flightplan (see previous posts!!!!read all posts!) is more then 30 min on a 767)
Again: almost complete responsability lies in zrh apt authority, not with the crew who did a good job.