It seems to be part of a push from ACMA to clamp down on importation of a range of devices that are in breach of or arenāt certified against Australian regulatory requirements.
I donāt think we have any hard evidence but yes I think itās a reasonable hypothesis that the clamp down is a result of the trouble the tens of thousands of uncertified devices caused ACMA in the lead up to and the aftermath of the 3G shutdown and the intertwined new emergency calling regulations.
Ah, so the other networks will āallow itā, but not sure it will succeed (again, due to the absence of testing and hard cold facts). This makes the engineer in me twitch uncontrollably. 
Thanks for that!
Weāve never had cause to use 000 so am curious as to whether our call would get through.
Part of the trouble is itās not as simple as that.
Multiple people in this thread can attest that they have either accidentally or in a time of need reached 000 from their FP5 (myself included).
But that doesnāt prove that it would also work when I wasnāt within range of my normal network. Or that it would work without a SIM installed. Or that it would correctly traverse the cascade of mechanisms that should be tried in what order. These are the sorts of things an accredited tester can test in a controlled environment, but is hard-to-impossible to determine via individuals doing random things in the real world. Hence @dt90125ās twitching as an engineer.