When I flew as crew, we were trained to initiate an evacuation in the event that we considered the aircraft was in a 'clearly catastrophic' situation. This is obviously left open to interpretation, but anybody with a few brain cells should be able to work out what may require an evacuation and what wouldn't.
Assuming the situation is as was described in the report, it sounds like the Cabin Crew did exactly what they should do. The report doesnt say the fire was in the cabin, there was a bit of smoke. What would the pax rather, that the crew opened the doors with the aircraft moving? So that the slides at doors one disappeared through the engine?! The facts on this incident are not known, so lets not have the usual trial, verdict and sentence all at the same time.
My personal view is that the crew would have had no choice but to pass this sort of information back to the flight deck, not necessarily to seek permission to evacuate but at least to get the aircraft stopped and shut down!!