My understanding is that the reason for the Vulcan being grounded is due to the Design Authorities withdrawing their support. I can see their reasoning as it is near impossible to guarantee the integrity of a single complex aging aircraft. Even if a strong case could be put forward to reverse their decision it does not help the case if the aircraft appears to be operated outside of it's permit.
On the other hand...
Wish I had been one of the lucky ones to have witnessed that roll. No harm done and what a way to sign off her flying career.