For the CHL yes. And there are a good number of CHL players who are better defensively, they just currently do not take on that role because their offensive talents are required.
Look at every elite defensive player in the NHL, what is the one common denominator? Foot speed. Datsyuk, Bergeron, Toews, Kesler, Peca, Madden, Lehtinen.
It showed in the world junior. Gauthier looked great killing penalties in a box when he did not have to move. Outside of that he was a pylon. He was blown by in the neutral zone every time.
He does play smart, and he works really hard to overcome a few deficiencies then yes he can be an NHL player, but he has a long way to go.