Trump, a profound nationalist, is often described as an isolationist with regards to his foreign policies, namely his strong opposition to NAFTA (North American Free Trade Agreement). This in particular would greatly affect Canada in terms of trade policy, jobs, unions, a large part of the Canadian economy, even the exchange rate if he were to actually win in the general election this November.
Let's imagine the prime minister went for it. Let's imagine he called Trump a fascist and urged U.S. Republicans to disown him, to shut down the circus. The story would make a much bigger splash than that photo of Trudeau striking a yoga pose on a desk shot in 2011 and inexplicably inescapable this week.