Quad is a myth. Australia's commitment to a China-containment structure is inconsistent. Morrison is just putting up a very seasonal "tough guy" act.
Way too many Australian businessmen have huge stakes in trade with China (resource exports). ASEAN desires equidistance from the west and China without stepping on either's toes.
The US is a waning power in Asia. Its days are numbered here unless it can dump serious capital into sizeable counterweights against China, such as India, Japan (revival of its economic vigor back to 1980's levels). It needs to unshackle India and Japan from its "strategic balance" calculus (this would involve cutting Pakistan loose and start throwing its weight behind India on matters like Kashmir).
Trouble is, the US is in for at least 15-20 years of leadership vacuum, and the likes of the EU, India, and Japan must fend for themselves. This means we must convince the US to look the other way while we develop our national power to be more resilient to China.