That's correct. From a reading of the bill, you'll see that one clause provides that the Government of Canada will inform the governments of foreign countries that a province is able to negotiate and enter into a treaty on its own. You asked me why Quebec wasn't doing it. That's precisely because Canada has to inform foreign countries of the fact that the province is able to negotiate and enter into a treaty.
On March 10th, 2011. See this statement in context.