Alliance would have difficulty proving that a vaccine was required due to the inherent nature of the job, particularly for non-customer facing roles such as pilots.
Qantas would have more luck mandating a vaccine for aircrew if it was required for international travel due to the various government border requirements. That would be a different argument.
Whilst I am pro-vax, I am anti- anything that chips away at fundamental human rights, such as the right to refuse a medical procedure. There is a principle at stake. I wonder if this will see the inside of a courtroom?