From an operational perspective it is absolutely the correct solution to divert to another station with staff, handling etc, although I do think had Edinburgh been available it would have gone there first. Prestwick is an alternate but may not have had the relevant RFF cover in place when the crew elected to initiate a diversion. I believe PIK is CAT 7 (?) but Emirates may require CAT 8 or 9. Judging by the poster from NCL above, bad weather after arrival played a factor in the crew running out of hours, which couldn't be foreseen. Don't get me wrong, I would have liked to see this flight in Prestwick (Etihad use EMA as a weather div for MAN despite having no staff there) but the diversion was a logical one for the crew and airline.