a passenger initiated or uncommanded evacuation can be a dangerous thing.
panic can lead to this and it can be deadly.
however we can all remember the british air tours 737 that burned on the ground with passengers patiently waiting for instructions from the crew.
There was an article saying that the fa/s were being scruitinized by the FAA and the airline for starting the evacuation.
I agree with the above post. And sadly, we probably will never get the whole story.