The way the statute is written is important and you've flipped it somewhat while adding your own conditions...
Part 3-2—Consumer transactions
Subdivision A—Guarantees relating to the supply of goods
54 Guarantee as to acceptable quality
(1) If:
(a) a person supplies, in trade or commerce, goods to a consumer; and
(b) the supply does not occur by way of sale by auction;
there is a guarantee that the goods are of acceptable quality.
(2) Goods are of acceptable quality if they are as:
(a) fit for all the purposes for which goods of that kind are commonly supplied; and
(b) acceptable in appearance and finish; and
(c) free from defects; and
(d) safe; and
(e) durable;
as a reasonable consumer fully acquainted with the state and condition of the goods (including any hidden defects of the goods), would regard as acceptable having regard to the matters in subsection (3).
(3) The matters for the purposes of subsection (2) are:
(a) the nature of the goods; and
(b) the price of the goods (if relevant); and
(c) any statements made about the goods on any packaging or label on the goods; and
(d) any representation made about the goods by the supplier or manufacturer of the goods; and
(e) any other relevant circumstances relating to the supply of the goods.
(6) Goods do not fail to be of acceptable quality if:
(a) the consumer to whom they are supplied causes them to become of unacceptable quality, or fails to take reasonable steps to prevent them from becoming of unacceptable quality; and
(b) they are damaged by abnormal use.
The requirement as written in law is that a product
must be of acceptable quality which means it must meet all the conditions within in (2) for it to be considered of acceptable quality. It could simply fail in any one of these mentioned conditions for it to be considered "not of acceptable quality"...
As written, there is no requirement that a product must be unsafe, or can't be easily be repaired, or some other condition you specify for a statutory warranty claim to be made to the courts.. It's required in law for the product meet all conditions mentioned within (2) else to fail in just one condition means to "not be of acceptable quality"
As is, GPS navigation units are purchased to help people get from A to B, doubt anyone can argue against that point. And to meet such a use case requires accurate map data which implies periodic map data updates are required. Without such periodic map data updates the routing accuracy can't be provided (where you can be sent the wrong way down a one way street) or in some cases the ability to route is completely lost (since the required area isn't within the map data).
It is the fact that map updates must be provided for a GPS to continue to be functional over time. Without map updates, routing gets progressively worse and worse (as streets change, get blocked off, become one way streets and/or speed zones change over time) unless you are unlucky and live in a new area (in which case you wont have the streets within the current map data and it was always a **** product that could never be fit for purpose unless updates were provided but they never were). The issue of whether map updates are provided free under warranty or a paid for purchase during or post warranty isn't the guiding issue here. The problem is that no map updates are being provided at all, even for those Holden vehicles still currently covered under warranty
The fact Holden isn't willing to provide the map updates or alternatively free up Mylink updates so others can provide them IMO isn't an excuse that Holden can use to overcomes the failing fit for purpose problem. IMO such can't be an excuse to throw away the primary purpose of the GPS unit that people payed good money for (or throw away that vehicle and buy another as much as the manufacturer would love that).
The average consumer expectation that forms part of the implied agreement that map updates will be periodically made available can't be so easily dismissed by Holdens crying poor. If they don't want to provide map updates and don't want to unlock thMyLink so others can provide the updates, then maybe they should refund people the cost of their sat navs since they can't make full use of them.
Yep, the courts requiring Holden to release a Mylink firmware to remove any requirement for a proprietary wrapper of the map data doesn't infringe GM/Holdens IP rights acording to your reasoning any more than the EU requiring Apple to sell an iPhone with usb-c port and charger. May be there is hope for you
But if only our regulators has balls