Obviously the reason why the UK CAA is moving so fast on this is that they'd be in a very poor position - were there to be a repeat. There have been enough instances of this in Australia where about 70 BAe 146 aircrew have symptoms and many have been permanently grounded due to sensitivity and greater susceptibility. Some have permanent disabilities.
Possible incapacitation of both pilots is one emergency that cannot be ignored. It will be interesting to see what sort of "fix", short of withdrawing the aircraft's type certificate, can be made - that won't simply be lip-service.