"I am disgusted and appalled by behaviour that would see Australians come and set fire to such a symbol of democracy in this country," he said.
He's calling what's going on in Australia right now democracy?? I'm afraid, sir, that this is indeed how Australia works now, by your own hand.
Have there been some issues in Australia with regard to COVID? Yes. But those have been caused by STATE governments, not the Federal government. Scott Morrison, as Prime Minister, has had no real control over any of that because of the way Australia's constitution puts all power relating to matters of public health in the hands of the state governments. The Federal government has virtually no power in this area, and cannot overrule the states. Morrison has been trying, throughout the pandemic, to do everything he can to get the states to behave reasonably but he doesn't actually have much power in these situations. Americans (and not just Americans, anybody outside Australia) seem to have this assumption that the Federal government 'outranks' the state governments and can somehow tell them what to do, or overrule them. That isn't how Australia's constitution works at all. The constitution was written in the 1890s by the state governments, who already had something close to sovereignty and independence. They chose to unify as a single nation for a few purposes - primarily international trade and defence. The federal government also eventually got power over foreign relations but not until around 1940 (before that, that was still handled from London - so was a lot of defence). Outside of the domains the states specifically agreed to hand over power to the new Federal government they were creating, the Federal government has no significant power - the states didn't want to give up their powers. And critically one of the areas they kept control of was anything to do with public health. And that is why the state governments have been running virtually everything related to COVID.
If this fire had involved setting one of the state Parliament's on fire (especially that of Victoria), it might have made sense as a COVID protest. But it isn't related to that at all - this is a result of protests by indigenous activists who want something they refer to as 'indigenous sovereignty' - exactly what that means is complex, but it's not a recent thing and it's nothing to do with COVID.
And labelling that way, means diverting attention away from the actual far-left groups that do want to overthrow Australia's constitutional law, and, ideally, kick out anybody they don't regard as indigenous.