If I had the finances and the (now insider) knowledge that HP...

If I had the finances and the (now insider) knowledge that HP enjoys, a Liontown-type strategy is exactly what I would follow. Buy 10% as soon as you are confident the project is viable; short the hell out of the stock for months while the management is dithering and panicking; accumulate (probably in assorted small pockets with funny names); push the SP down as low as you dare without spooking the extra potential offtakers you need; consolidate a 19.9% stake while keeping lots more shares aside; give an ultimatum to GL and BOD to secure the remaining offtake agreements needed to reach 85% or be replaced; then take over the lot.
No tears for retail holders of course. All we can do is hang on and hope. If ARU is taken private, we could still lose our shirts.