If he shows, he'll just say he is only one out of the whole GB and has no individual power.
He won't lie or deny the policy, but will say they "cannot go beyond what is written " (yes, blame Jehovah).
Remember, the legal system is not interested in debating correct scriptural interpretation on this anymore than it is on the JWs blood transfusion policy.
He will say that JWs must obey all laws that are not in direct conflict with God's law, and if the law in Australia changes to require mandatory reporting by elders to the secular authorities, the elders will be instructed to comply with that.
It's not possible to reason with brainwashed religious fanatics who hold primitive mythology to be immutable truth.
The onus is on the civilised and enlightened world and it's legal system to intervene to stop the evil fruitage religious fanatics produce.