To understand this better, one needs to understand the Australian psyche! When you become an elite sportsman in Australia, you become akin to the Royal Family, aka the chosen ones, the elite, you've made it, and you are the winner, the rest 'runners-up'.
We are in the lead up to the most famous of 'cricket series', here in Australia, and the past, and present adorned greats, are spouting the usual vitriolic diatribe, to fuel the flames of discord, to attempt to undermine the opposition. Instead of waiting to step onto the playing field, and letting their skills become relevant, they choose to mentally intimidate the opposition, which they call sledging, because they think it's funny.
They know that Piastri is a great, and if he doesn't win anything, it's not his fault, the world will be blamed, and any non Australian victimised, for always being against US.