The article makes it abundantly clear that this is not the case. The first three paragraphs alone have most of the effective article impact.

"When Australia’s renewable energy portfolio reached its important milestone on Wednesday of providing 50 per cent of the main grid’s demand for the first time, one solar farm couldn’t be part of the fun, and had to look on from the sidelines.

The sight of wind and solar farms being switched off when wholesale electricity prices fall into negative territory has become increasingly common over the last few months, particularly in Queensland and South Australia.

But the facility that appears to have been affected the most has been the 95MW Tailem Bend solar farm in South Australia, owned by Vena Energy and operating since earlier this year."

Further reading shows that coal plants rarely need to shut down as evidenced by:

"It’s common to see wind and solar farms switch off when prices go into negative territory, or get close to zero. It happens either because their off-take agreements oblige them to do so, or because they are “merchant” facilities that take the spot price and don’t want to be paying other parties to take their output if prices do go negative."

Coal generators almost NEVER pay for arbitrage in Australia because of various specific agreements (and limits to the arbitrage that is possible in many areas.) It is almost the exclusive domain of wind and solar plants.