The modeling accuracy wrt the altitude of the cloud is quite high hence the risk assessment conducted by every airline that flys into Australia except Qf and tiger, allowed for continued operations.
But hey what would airlines the likes of Cathay, emirates, ethiad, south African, Singapore, Malaysian, united and virgin know.......
I'm SLF so not qualified to speak about the aviation aspects.
But from a purely risk-assessment framework: If you had an uncertain risk that impacts all your assets versus the same risk impacting only a few of your assets wouldn't the rational response be different?
I was speculating that might reflect in the native Airlines being less likely to operate? I am assuming Quantas saying "we'll fly 10% of our routes for risk hedging" was not an option.