I guess it depends on what type of multi "operational scenario" falls under your classification.
The defence force obviously needs to be multi facetted, but designed and structured for a particular region certainly isn't poor forward planning imo.
There's a counter argument to your point being you risk being a 'jack of all trades and a master of none', ineffectual in the face of a well prepared opponent precisely designed for particular operational scenario's. There's evidence of this right throughout history.
Without beating around the bush, he's obviously referring to China, I think it's safe to say you can throw the rule book out the window for the next decade in regards to defence procurement and what we may or may not have done in the previous 30-40 years as an indication of what we might do in the next decade.
I very much think we will tailor our decisions to a potential conflict with China in the Pacific and the operational scenario's surrounding the consequences of that.
There is a difference between missions and region though.
From a geography point of view, it is absolutely right that we focus. In my opinion, one of the key undersold points of DSU/FSP20 was the explicit focus on the region. While flexible in where the boundaries lie (I mean, the Indo-Pacific does stretch from Africa to South America and Antarctica to the Arctic...), focusing on the region does aid in force design.
From a mission view though, that's harder. The reality is that we have a number of tasks given to us by Government, and there are a number of tasks that (generally speaking) only we can do. Beyond high-end warfighting, there are tasks where the ADF needs to do something - Timor-Leste in 1999 is an example of lower end operations, but even 'simple' things like RAMSI need a military presence, even when the leading agency is not the ADF. There are also a subset of capabilities that can only really be held by us, everything from long-range bulk transport to support Antarctic bases through rapid surge SAR forces to rescue British yachters up to specialised threat response in aid of the civilian police. With all of that in mind (and I haven't touched on humanitarian response), your high-end warfighting capability is not all that's needed. As cool as tanks and F-35s are, they are pointless in helping a neighbour restore faith in their political system or helping two internal factions make peace.
In addition to all that, even a phrase like 'high end warfare' ignores the reality of that. It's not just the shooting part, its the logistics and the security. Even little stuff (and for lessons identified see Iraq and Afghanistan) like what happens to the town after 7 Brigade seizes it and continues advancing? We become required to provide life sustainment, including law enforcement, in similar ways to our help in Timor-Leste and the like.
Beyond that, there is no clear, unambiguous, existential threat that would cause such specialisation. Israel has one, hence their force design (especially in the 60s-90s) being so focused. NATO until 1991 was similar. You could argue Poland is today based on their political and force design decisions. We did it in 1941/42. But, beyond the hand waving, let me honestly ask if such a threat exists for Australia. And, before we jump to China, look beyond the Department of Defence. If there was an existential threat that required us to shed tasks and focus on high-end warfighting exclusively, what would the other Departments be doing? It would be part of a Governmental, strategic response - so would we continue to trade with a threat? Would we continue to seek uni students and train the threats next generation? Would we allow threat investment? Would politicians at all level be allowed to have open ties to the threat?
Fundamentally, the single unique task we do is high-end combat. And that's where force design focus should be. It's why we buy tanks, fighters and submarines, despite being decades since they deployed to do their actual job (submariners - shush. I know). It's why projects that buy weapons that are useless for helping with bushfires and support nodes in excess of anything needed for floods is so vital. And it's why many years ago HADR did not become a force design driver. But - we have to remain flexible. And until there is an existential threat, that need is unlikely to change.