I am thinking that at least the following should be done before "abandoning" by a responsible government.Probably constitutional illegal. But in emergencies, law doesn't matter. I am also interested to see what they will do.
Embassy sends out orders to all citizens in India to evacuate, with a deadline. Embassy provides pickup transportation if necessary. All will be send back to Australia. All evacuee will be quarantined on arrival.
That was what China did during the Libya crisis.
Only the ones who refused to obey the order should be banned to return.