Canada could make a request for him to serve in sentence back in Canada and could decide to release him early. However, this is not going to happen with a Conservative government in power.
Considering Harper couldn't be arsed to bring Omar Khadr[1] home, I somehow doubt they'd budge for Emery. That, and, Emery's a gigantic dick who spent years forcing the government to arrest him. He's not exactly a sympathetic character.
There are mechanisms that nation-states have used to free people imprisoned in other nation-states without the cooperation of the imprisoning nation-state -- they frequently, however, have significant repercussions in the relations between the nation-states that make it inadvisable for a less-powerful nation-state to use them against a more-powerful one even if they have the capacity to acheive short-term success.
The exact level of shared culture necessary to have a "nation" in the sense of "nation-state" is infinitely debatable, but the statement at issue is just true of states generally, so while your point might arguably be true, its not all that relevant.
