The issues isn’t the likelihood of combustion but the complexity of stopping the fire once it’s into the batteries.
If a fire gains intensity and becomes significantly more complex to deal with whilst in an environment where the floors/walls around them are at risk of collapse in these extreme conditions then a plan needs to exist on how to either protect the batteries in the event of a fire or deal effectively with the fire once it’s got into the batteries.
I'm Autistic, if I say something you find offensive, please let me know, I can guarantee it was unintentional.
I'll try to give my honest opinion but am always open to learning.
Mark