Look at China's recent environmental catastrophe where the air in its industrial cities is so polluted residents are buying cans of clean air to breath. Would the environmentalists rather see the Canadian oil go to China where the damage to the environment will be exponentially worse or to the US with strict anti pollution laws?
Yes they would.
You see they, like Diane Feinstein, have ‘investments’ in China and make money from the pollution and loss of American jobs to China. They want nothing to change.