Many athletes in Canada hold dual citizenships and have competed for other countries. The most recent one I can think of is Dale Begg-Smith, who won gold for Australia at the last winter Olympics in men's moguls. Dale, who was born in Canada and holds dual citizenship, started skiing in Canada but found the training program too restrictive. He moved to Australia where he was given more latitude to focus on his business interests. Ironically, his win bumped Canadian Marc-Andre Moreau down to 4th place and off of the podium.
Anyway, switching allegiance is done for any number of reasons. Often, athletes who don't qualify for the Canadian national team have the opportunity to compete at a higher level by joining a program with less depth. There's certainly no malice intent here but when I heard that Duke was considering this option how could I not picture this movie...

Duke! Paddle Learnings of Canada for Make Benefit Glorious Nation of Serbia

Eurovision 2007