International law cites the right to self-determination of peoples as a pillar for all international law, and the UN's charter says:

"All peoples have the right of self-determination. By virtue of that right they freely determine their political status and freely pursue their economic, social and cultural development."

And also includes in its declaration of the UN's purpose:

"To develop friendly relations among nations based on respect for the principle of equal rights and self-determination of peoples, and to take other appropriate measures to strengthen universal peace"

Either Canada's, and other Western governments believe in international law and the UN's charter, or they don't.