I guess what I'm trying to point out here is that - according to my calculations - the aircraft captain decided to divert about 700 nm to the west, perhaps 1 hour 45 mins flying time. That, to me at least, indicates that he did not have a serious (aviation) problem on board. Especially with at least four International Airports with runways in the 10,000 foot range in the immediate area.
The captain did not have a serious (aviation) problem on board, that is why he only declared PAN and said emergency vehicles were not necessary on landing. Then the time to get down to a safe landing weight was about the time to fly to YVR a very suitable airport.
I would suspect that the reason that all the rear crew were immediately evacuated to a hospital is to get a blood sample from each of them before traces of whatever caused the 'fume event' dissipated.