The incident aircraft was an Airbus..
However, they would of had available to themat least two other sources of information regarding the status of the hold once on the ground.
The cargo temperature indication and reports from Fire Service over the radio who would be scanning the hold with their thermal imaging equipment.
This is why Airbus feel confident enough to say that you may disembark the passengers not evacuate them.
A decision to evacuate must not be taken lightly as you will cause injury to passengers.
With the fire service report that the hold is not showing signs of heat, the indication that everything is normal on the cargo temperature indication.. Coupled with firefighters standing by outside the aircraft with the capability to fill the hold with agent within a few seconds.....
Can you really justify causing injury to passengers as opposed to a controlled disembarkation by steps? Keeping open the option to evacuate if the nature of the incident changes.
If the fire service reports that the hold is showing signs of heat or smoke issuing then it is a completely different situation.