Australia makes and exports different things to the USA. For example, there are some parts of their bomber planes that only an Australian factory makes. If we stopped trading it, they couldn't buy any more of those bombers.
There's also the impact of solidarity, where if we stop trade, then other countries are more likely to do the same. This effect has happened with previous blockades and with the general sentiment towards the conflict in Western governments, one country takes the first step and others soon follow.
It also means that, as smaller partners stop trade, the US soon becomes a single point of failure, where a port strike or community blockade (as some in the USA have done before) has more direct impact.
That's not exactly my point, it's more that our current political economy penalises pro-social behaviour (a business is more likely to be out-competed and fail if they actually treat their workers and customers well, so it's an exceptional thing to see) and sociopaths are rewarded for profiting in this system, their gain comes at our exploitation so they're effectively rewarded for hurting us.
If we can restructure our political economy so that sociopaths are rewarded by contributing to society, then their own competitiveness and greed is much less of a problem. For lack of another better developed-world example, look at how China keeps their billionaires on a leash^[https://redsails.org/china-has-billionaires/#fnref14]. Now obviously there's plenty of problems in their political system and some would say they their billionaires are still a problem despite them being dominated by the government, but it's an example of an alternative to the oligarchical system we know, proof that there are successful ways forwards which are applicable to our economies, even if we don't copy them exactly (that would be silly).
(On top of this, a society is certainly capable of detecting and ostracising or punishing anti-social people such as sociopaths. The problem is that the most important ones are effectively out of reach in our society since they have a police force protecting them and we have a more alienated, disorganised society)