Associate Professor Karl-Heinz Wyrwoll has littered his article with qualifiers:
* During the last few decades, human-induced climate change has been a pervasive theme in the scientific literature.
* Ruddiman’s research, while not without its critics, suggests that these resultant climatic changes ...
* This is the idea that early agriculturalists caused an anomalous reversal ...
* He showed that vegetation clearing, overgrazing and burning may have had an impact ...
* Tom Lyons’ “bunny fence” experiments have drawn attention to likely climate impacts and feedbacks ...
etc.
I'm neither agreeing nor disagreeing with the notions put forward, just highlighting that the article is not as you paraphrased it.
There is evidence that aborigines affected the climate, but there is not proof.
We back burn areas most likely to cause uncontrollable bushfires in the future
Most of the continent requires fire, with the notable exception of Tassie and some rainforests scattered throughout the mainland
Adaptation and species selection has resulted in what we have now -- as distinct from finding ourselves in a land that happens to need regular burning.
Contrast us with comparable latitudes (15-35 from the equator) on other landmasses.
In Brazil, transpiration from the Amazon rainforest produces more water vapour than the amount of water transported by the Amazon river. This is known as an atmospheric river (e.g. [1]) and is now seen as critical to the Brazilian climate. I think the theory is that wide spread burning in Australia destroyed the atmospheric river there, which led to a much drier continent than existed before humans arrived.
[1]: https://www.noaa.gov/stories/what-are-atmospheric-rivers