JetBlue trains the flightcrews to not indicate a direction for evacuation. This was a change from how we were initially trained with the explanation that the FAs were taught to assess the risk before they opened a door. I agree that the FAs at the exit right in front of the engine can't assess fire out the tailpipe and can't tell if an engine is running or not. We do what we're told...
Speculation was that they ingested an iguana. This would make a great story, but I was speaking with a colleage in Tech Ops this morning and he says IAE confirmed it was a bird ingestion.