Well, I'm not sure that having an all-Canadian service would be a violation. However, if you had a situation where the Canadian government decided they wanted to have an all-Canadian service and they would fully fund it and require others to pay into it, then, yes, foreign services might say it's an unfair advantage to a Canadian-based service, and here is the cost or the commercial effect. The U.S. would be entitled to levy measures of equivalent commercial effect, and they could target whatever sector they like.
On February 19th, 2020. See this statement in context.