Finally someone has sense! It is all a bunch of scam to get money from both sides.
Cliff Notes: At hypersonic speed (low altitude trajectory) the heat generated by the missile is so high that they can easily be detected by satellite. At high altitude trajectory non hypersonic missile is actually faster than hypersonic missile.
It doesn't make sense that Australian politicians supposedly "owned" by China would be signing deals that are not in China's interest. Increasing US allied naval power in the region is clearly not in China's interest. They can always steal technology direct from the US.