I've got a simple question?
How realistic is it to expect aircraft crew (both cabin and flight deck) to determine with absolute certainty that a fire (and where there is smoke there is combustion of some type) is not potentially immediately catastrophic?
To comment "it's a knackered fan" in 20/20 hindsight is not at all relevant to making a prudent real time decision. Had this been a fire similar to the recent one on the Russian airliner how would people react to the quick decisive decision of the cabin crew saving scores of lives potentially?
However having a passenger or two run thru the blender would have been a major screw up....so who in there right mind orders an evacuation without informing the flight deck directly for both their own safety and to make sure the eggbeaters are off....