So the lesson is...? If there is an unusual occurrance and if there is time, as there was in this case, contact the cockpit crew before taking any action.
An evac occurred on a Swissair MD-80 in CDG during pushback - much to the surprise of the cockpit crew - due to smoke from a ground vehicle entering the cabin and setting off the rear toilet smoke alarm, which was similar sounding to the evac signal fitted at that time.
Following that incident, the books were revised as to definition of when the cabin crew could initiate an evac. on ground - including the stipulation that the aircraft stand still, as well as the catastrophic points (ditching, severe damage and explosive fire) mentioned above. At that time the tailpipe fire was even taught as an example for not evacuating.
Time passes, people change and history repeats itself unfortunately.