So, France sells the reactor to the Australians instead of the US. Either way, Australia needs to "come up to speed" on the operation/use of that power system, causing a delay in actually implementing the program making the current sub force outdated by that time.
Australia could be more interested in an alliance with China or Russia, who also could have sold them nuclear tech, which they still would need time to learn how to operate, causing serious delays.
So, it has nothing to do with who they chose to do business with. The mere decision to switch to a nuclear sub force sets their time line back, no matter what.
Australia's choice to make...no?
Good question. Originally, the Australians wanted a diesel submarine. Therefore, a nuclear submarine was re-designed for them.
France is supporting Brazil to built a nuclear submarine, Álvaro Alberto . There is an obvious difference to Australia: Brazil has its own nuclear industry and is developing its own reactor.
My guess would be: France would have sold also the reactor to Australia, but Australia is more interested in the alliance with the US than the submarine and therefore is accepting a 6-9 year delay of the program, which will cause the Australian submarine force to be completely outdated in the next decade before it will be revived sometimes in the 2040s.