I hate to get all ad hominem here, but the fact that it comes from an Australian journal is just a tad bit self-interested. It reminds me of the Chinese scientists who keep insisting that humans evolved in China, not Africa:
https://www.news.com.au/technology/science/evolution/chinese...
The far better argument IMO would be "it's a lot easier for new discoveries to be made by and reported in the the country they occur in so it isn't necessarily surprising the initial challenge would come from and be reported in that country". The China human origin one had more problems than just initial suspicion but this one will probably sort itself out into overall consensus in time and I wouldn't be surprised if it ended up being true. However it's probably still getting more self-attention than it would if the discovery were somewhere else in the southern hemisphere than Australia and there is nothing wrong with keeping that in mind regardless where you are or what you currently think.
The assessing motivations game has no role to play here, and no destination for that matter. You could spend the next millennium trying to determine whether this particular piece of research was published in an Australian journal for nationalistic reasons (and whose reasons?) vs whether it just so happened that a piece of Australian research got published in Australian journals (gosh!) vs whether the putative 'research must be reviewed by peers from outside the region' rule (created in an HN thread) was equally applied to default US and EU based researchers. None of it would illuminate the truth or otherwise of the proposed idea.
> Together this weighty band of experts has just published a paper in the scientific literature that’s likely to be seen as landmark in our understanding of life on Earth.