That said I think there is a place for both. Frigate convoy protection through the remote areas, then shore protection in the littoral waters around key ports and straits, all with sub and surveilance air cover as well.
One of the fundamental problems with a land-based AShM capability is that those critical SLOC chokepoints are essentially all outside of Australian territory or control. This in turn means that these hypothetical Australian AShM batteries would not be in position at the outbreak of a conflict and would need to be deployed from somewhere else. To provide a better scale for the issue, the straight line distance between Darwin and Singapore is roughly the same distance as between Perth and Sydney. This complicates any sort of rapid build up of AShM batteries, assuming that Singapore, Indonesia and/or Malaysia were willing to permit Australia to forward deploy such units, since airlifting such units would be a fairly resource intensive operation over such a distance. If those countries were unwilling to permit Australia to forward deploy the batteries, then Australia would likely have to make a forced amphibious landing to get the batteries into position. Doing this would likely require significant air and naval escort in order to get the amphibs or landing craft to the appropriate landing sites. If such an Australian deployment was opposed, then the situation gets massively more complicated and would require significantly more resources to get the batteries established and the keep such a deployment operational.
Now the cost of a battery of AShM launch vehicles as well as the missile loadout would likely be significantly less that of a single, modern warship, a warship can transit 3000+ km of potentially contested waters to maintain a distance presence for days or weeks at a time, whilst land-based vehicles cannot cover that distance over waters on their own.
I would be suggesting deployment to countries like Fiji, Vanuatu, Solomon Islands, PNG, Timor, Christmas Island, coco leaking and along the Australian coast line. Well position strikemaster units forward deployed during a war in numbers.. as you could build 100’s of units for a fraction of the coast as one frigate. All built in Victoria. Each unit could comprise of a couple of strike masters, a strix long range drone for isr and targeting and a protection unit. Mass produced forwarded deployed would not only protect our near neighbour’s but Australia at distance.
Note the bolded text. All of these are foreign nations and unless/until Australia is ready, willing and able to invade them, Australia cannot deploy AShM batteries without permission. Further more, of the entire list, Fiji, Vanuatu, as well as the Australian territories of Christmas Island and the Cocos or Keeling Islands are so far apart that land-based AShM would not cover the entirety of the distance between them and the next nearest land masses. It is a little under 1100 km between the capitals of Vanuatu and Fiji. It is nearly 1,000 km between the Cocos Islands and Christmas Island, the next closest inhabited land mass. Unless Australia were to acquire a stock of extremely long-ranged land-based AShM (i.e. something with 1000+ km range, rather than the ~250 km range of NSM) lots of places would be out of reach. In the unlikely event Australia did acquire something like land-based Tomahawk AShM, that potential range increase would also just make the situation harder.
Using NSM as an example, a single launcher site could potentially cover an area of some 196,000 sq. km which in turn means that Australia would need to be able to monitor ship traffic within that distance, for each launch site. That kind of area volume to cover would need more than a few drones to monitor that great an to keep under surveillance. If we were to consider something like land-based Tomahawk AShM, then the area of potential coverage for a single launch site would be a little larger than that of mainland Australia. This large an area would then require some significant resources just to monitor for potential adversaries, making the whole proposition a losing one.