James Naismith was a Canuck.
So what? That doesn't make the game Canadian. Every other aspect about the development and history of the game is dominated by the U.S. The fact that the first basketball game was played on American soil by Americans is at least as significant as the nationality of the inventor in establishing a national claim to a game. Particularly, when the inventor was in the process of becoming Americanized himself, although it was years later when he formally became an American citizen.