The actual deadline for completing the census is 23rd September, so anyone who fails to do it today will not get fined and can complete it in the next 4 weeks or so.
Unfortunately the messaging from the AUS Gov seems to have forgotten to point out that actual deadline day.
So this is essentially a self inflicted Denial of Service attack.
What are the penalties in Australian law for this, and who in the Australian government census "marketing" department is going to get prosecuted for this?