Interesting that the crew apparently were well enough to collect their luggage before deplaning ahead of the PAX. Kind of like PAX taking hand baggage during an emergency evacuation. It seems clear that much more exists to this story than is currently being revealed.
I was also struck by the letter given to PAX as they arrived at YVR seen in this link
British Airways flight diverted to Vancouver after cabin crew becomes ill - British Columbia - CBC News It tells them that their first opportunity to rebook would be by calling BA beginning at 0400 YVR time. Why is this? Is it because BA does not maintain a 24-hour call center for such issues? In any event, this is brutal. You are dumped in YVR at 2330 local. If you are lucky, you will only be getting into bed at a hotel by 0200 -- and if you want to be first in line for rebooking, you need to wake up at 0400.
I had thought that US airlines were the champions of nongraceful service recovery. But if this is correct, BA would appear to be a strong contender for the title.