Does anyone really think that if a 777 had total power loss, and no reason could be given straight away that they would let the rest of the 777 fleet keep flying??? I think not......
Even with the AAIB initial report, these are not instantaneous, clear-cut decisions. There is some investigation to accomplish before it can be determined where the seeds are - in this aircraft, or fleet-wide. Also, as unseemly has it may be to contemplate, the realities are such that commercial pressure is a factor. Such factors will be a part of a very large picture even now.