Canada is a country that is a democracy, generally supports human rights, and doesn't oppress it's people. When we get shale oil or any oil from that kind of country, that's what you are supporting.
If you are buying oil from Saudi Arabia, you pouring money into the coffers of a country that is oppressive, doesn't have a concept of human rights that we understand, and uses it's money to evangelize the world with their version of Islam, one of the most hardcore and militant versions. That's conflict oil.
Now we need oil so we are going to buy it from someone, but if I had my druthers, I would rather buy it from Canada than Saudi Arabia.
so would anyone.. so what's the catch?
