Politics aside PBs, especially ones built to commercial standards and attempted to be maintained under a commercial arrangement, are not fit for purpose. Leave the PBs to customs, fisheries whoever (probably the super department of Immigration and Most Excellent Border & Sovereignty Protection) and provide the RAN with warships.
Hopefully, local manufacturers see the opportunity and seek to exploit the successive government’s fixation on illegal immigration via the sea, and promote high end dual purpose assets that enhance both existing war fighting capabilities, and border/immigration control.
Offshore Combatant Vessels, Unmanned air systems, Maritime patrol aircraft and the like.
A multi-mission and helicopter equipped OCV would increase the RAN capability leaps and bounds. It would also ultimately have cost saving benefits, as we wouldn't have to use frigates (that cost over $200,000-a-day to operate) for border protection and immigration control.
The patrol boats are not designed for this task, and to state they are unsuitable for it is an understatement. Yet a frigate is overkill.
The problem and thus need is identified, the benefits are obvious and the opportunity for “add on” mission modules (ASW, ASuW etc) gives the manufacturers profit opportunities (making it viable). The potential for "mission module" value ads gives the RAN additional options in future warlike scenarios, but a baseline OCV (yet easily upgradable) solves an immediate problem at reasonable cost.
If we back away from the OCV concept, local manufacturer’s marketing/lobby/business development (and design) teams would have a lot to answer for.
I don't think all the blame should fall on the government, Defence doesn't buy a lot of votes in Australia, so it is up to Defence industry to present them viable,affordable and flexible options/solutions that lead them down a path to the decisions that are in their own best interests, and really the only sensible choice.