AB,
They're not grounded. There has been no communication to that effect from any regulator or the manufacturer.
Due to a lack of any real information the operators have, in consultation with the HSSG, elected not to fly the Pumas until there is something to go on.
The AAIB may well already be sure, from the pilots' accounts, that this is a CFIT accident, but will not say for sure until they have the CVFDR. If they were to put something out to the effect of : " there is nothing wrong with the aircraft, this was pilot error" the operators may very well start flying again.
Imagine then retrieving the CVFDR data and realising that there was in fact something very wrong with the aircraft but the pilots hadn't noticed (for all the reasons alluded to earlier in this thread).
The AAIB would be in deep sh*t for jumping the gun.