I couldn't agree more with
@Rob_TO
I've moved around quite a bit during my childhood and while there's a difficult transition period, kids adapt! (9 year olds especially)
I've heard the winter this year has been especially harsh, so maybe he's having trouble with the cold, but as Rob_TO said he'll get used to Canada in due time.
At 9 there is no way he is rational enough to be able to decide where he wants to live, and I doubt that he comprehends the impact leaving Canada could have on his life. (In relation to PR/citizenship prospects)