Canada the country, being a democracy, is owned by the Canadian people, not the king (just like the United States is owned by the American people, not the president). If Trump encroaches on the sovereignty of Canada it is an affront to the Canadian people. What the British think is of distinctly secondary importance.

I'm not sure you see the irony of your stance. You're complaining about the American president butting into Canadian affairs because it infringes on some supposed colonialist rights of an absentee king.