Did the Crew initiate the evacuation, or did a passenger panic when they saw flames coming from the Other Aircraft, and someone opened an Emergency Exit, everyone else followed ?
If you listen to the audio recording above, (post #17) at 32 seconds, the Captain (or F/O) says on Ground Freq,
"Mayday, Mayday, Mayday; West Jet 2425 we're evacuating.."
So the crew made a decision to evacuate based on information they had at the time. Not a passenger opening an Emergency Exit..