China is a concern for Australia whether the US is in the picture or not. Australia's interests are highly aligned with those of the US. The increased engagement from the US is being welcomed by most Australians, but the issue is really around the implementation.

AUKUS is one of these huge deals with the results coming many years after huge investments creating great uncertainty. That makes it easy to attack politically.

EDIT: What's missed by the original commenter is that Australia was already investing in submarines from France. If delivered, there would be similar outcomes. The project had just as much uncertainty around it and was off-track when AUKUS was announced.