Well, I'm not sure how they can. In order to comply with the PVSA, the have to stop in a foreign port for the cruise to be legal. Now, there was a time when cruise ships would make "technical stops" in places like Ensenada (on Hawaii cruises) for a couple of hours to complete paperwork (but no debarking passengers), but about 4-5 years ago it was ruled that "stopping in a foreign port" means they have to allow passengers to get off the ship in port.
I wonder if they just intend to pay the fine ?
However I do also wonder how they plan to get around "Canadian waters" which is what the ban applies to; it would require a fair bit of sailing out of their way. e.g. no Canadian Inside Passage.
SW