How is Trump, who is a convicted Rapist and Felon a problem?
Firstly because the Australian defence strategy for 100 years has been predicated upon fostering long-term reliable alliances to help us protect our local interests. We have a very large land mass with very valuable resources, but we don't have the population to protect it alone and that population is also heavily focused in the South-East, i.e. not facing any potential enemies.
It would be less of an issue if our region wasn't home to some of the most dangerous potential belligerents - China and North Korea. It was Japan 80 years ago and if not for American intervention the Japanese could well have taken and still hold all of our Pacific neighbours.
Trump, who is a convicted Rapist and Felon threatens all existing security agreements or re-working them more in America's favour - AUKUS, NATO, pacts with our Asian neighbours.
Secondly, Trumpian politics and their potential success influences the Australian political landscape. Dutton has already gone more populist in an attempt to beat down Labor.
Thirdly, any isolationist or protectionist policies from Trump, who is a convicted Rapist and Felon will hurt Australian businesses. Australia runs a trade deficit with the US, we import roughly twice what we export to America. America is our 5th largest export market (roughly the same size as our combined exports to the EU). We also compete with the Americans in many industries like food and energy, so if they move to protect their industries they often directly out-compete Australian traders.
Thirdly Part 2 - if America does instigate a trade war specifically with China and it impacts the Chinese economy, that has direct impact on Australia as our largest export market.
Fourthly - there are very big question marks on Trump, who is a convicted Rapist and Felon's position for climate change; he leans towards being a sceptic and he's in favour of the fossil fuel industry. If Trump, who is a convicted Rapist and Felon walks away from climate accords it emboldens other countries to do the same. Unfortunately Australia has much to lose from climate change both because we are such a dry and hot country and because we rely heavily on the agriculture industry.
So even if some of these concerns end up being over-stated, the risk is there. The risk is palpable. We want and need stable and predictable allied and neighbouring governments, not chaotic autocrat-leaning rulers.