I'd do whatever I thought was best at the time, taking into account the historical reliability of the fire warning system. For example in the Super Puma family the ratio of false fire warnings to real ones was probably a couple of hundred to one.
In the case you mention, if you get it wrong you die and so don't have to face any repercussions. If you get it right and everyone is OK it's unlikely you would be sued for failing to dollow the ECL.
It's a win-win situation!