I think you missed his point. He was talking about the monarchy which is a relationship between a nation and a particular set of individuals.

The relationship between two nations is different. Ideally it shouldn’t depend at all on who leads those nations but in practice it’s affected a lot. But I think it’s not wise for a leader to let their personal feelings about the leader of another country affect diplomacy. That’s Trump’s folly.

I say all this without a dog in the race, as a Canadian who likes Australians. I think Canada should work on improving relations with Australia and build a stronger partnership for mutual benefit.