I think I may have found something novel to say about this.
There are two points that I think are relevant to this issue.
1) Canada and the US do hundreds of millions of dollars in trade with China every year.
2) Governments have infrastructure built in to be responsive to the will of the people.
Yes, I am side stepping the issue of human rights. Honestly, I don't know much about it. What I do know is that those fighting the battle have a more vulnerable target than Google. That would be their government proxies.
That is to say that if Google in China is a problem it is indicative of a bigger problem that could be more effectively dealt with elsewhere. If you are of the mind that the government is not responsive to the will of the people and so it is not a more effective portal for activism in this respect, again that is indicative of a much bigger problem and I would start question the difference between your government and China's.