They have the legal right, but it would be politically awkward, and I'm not sure Trudeau is looking to annoy his base in Quebec to serve the interests of British Columbians, who have never been a part of the LPC's base and only recently elected more than a couple Liberal MPs.

Similarly, it's well within the Federal Govt's rights to mandate free trade within Canada, but they only had the political willpower to suggest provinces work together to reduce barriers.