Even if it takes Australia longer than expected to build up its fleet of nuclear-power subs, China will see this as a provocation and the start of a nuclear arms race in the region. Beijing might not immediately retaliate, but this agreement will eventually see it further invest in its military and could force other neighbors to pick sides in a Cold War-style conflict.
Australia must adopt this nuclear-powered submarine plan in order to protect the peace and stability of the region and guard against aggression from China. Its neighbors and allies should understand this deal as a peaceful one, not an act of war. In addition to defense, Australia will benefit from jobs created and technological advancements in its broader economy.
There's a 50% chance that Australia will commission its first nuclear-powered submarine by November 2036, according to the Metaculus prediction community.