Whilst it's poor of BA to not have rebooking policy in place when Ops actually push the button to cancel a flight, this is not an unusual occurrence. Sit tight for a few days, let the dust settle, and a policy will usually be available within a couple of days.
As far as I can see from the feedback above its not that BA are refusing to reroute anyone, just that they need time to get a policy in place that call centre staff can use to progress your request.
Agree with the comment to avoid CX at all costs at the moment, not only are the schedules subject to change, a transit through HKG puts you at risk of a quarantine if something goes wrong.