Its fascinating to learn that the AIP has no force whatsoever.
Even CASA FOIs would know that that’s an inaccurate generalisation. They may have been referring just to mandating diversions, but even that’s a brave call.
You don’t need to dig too far into the rules to find many links to the AIP, backed up by criminal offences. For example:
239 Planning of flight by pilot in command
(1) Before beginning a flight, the pilot in command shall study all available information appropriate to the intended operation, and, in the cases of flights away from the vicinity of an aerodrome and all I.F.R. flights, shall make a careful study of:
(a) current weather reports and forecasts for the route to be followed and at aerodromes to be used;
(b) the airways facilities available on the route to be followed and the condition of those facilities;
(c) the condition of aerodromes to be used and their suitability for the aircraft to be used; and
(d) the air traffic control rules and procedure appertaining to the particular flight;
and the pilot shall plan the flight in relation to the information obtained.
(2) When meteorological conditions at the aerodromes of intended landing are forecast to be less than the minima specified by CASA, the pilot in command shall make provision for an alternative course of action and shall arrange for the aircraft to carry the necessary additional fuel.
Penalty: 25 penalty units.
(3) An offence against subregulation (2) is an offence of strict liability.
Note For strict liability, see section 6.1 of the Criminal Code.
240 Authority may issue instructions in relation to flight planning
(1) CASA may, in relation to the planning of flights referred to in subregulation 239 (1), issue instructions about:
(a) the weather reports or forecasts to which a pilot in command must have regard in planning a flight; and
(b) the circumstances in which a pilot in command must plan for an alternative course of action (including the use of alternate aerodromes); and
(c) the information that the pilot in command must take into account in planning an alternative course of action including:
(i) the range and timeliness of the available meteorological information about the aircraft’s destination; and
(ii) the type and number of radio navigation aids that must be available at the aircraft’s destination; and
(d) the conditions that an alternate aerodrome must meet before it can be used as an alternate aerodrome.
(2) If an instruction under subregulation (1) is not issued in the form of a Civil Aviation Order, the instruction does not bind a person until it has been:
(a) served on the person; or
(b) published in NOTAMS or AIP.
(3) CASA may give permission, subject to the conditions specified in the permission, for a pilot in command to plan a flight without having regard to an instruction under subregulation (1).
[Bolding added]