In your mind that is the entire argument. In the real world the pipeline was built so tar sands oil could be developed in Canada. There is a really good chance without that pipeline those tar sands would have been at the very least less developed. Tar sands is very dirty oil. It creates more pollution to develop and more to refine.
I’m not a killjoy on oil but I’m not dumb either. The keystone pipeline serves as a way to develop some of the dirtiest oil on the planet. To say the environmental impact of those oils is less than what we currently produce and import is disingenuous.
All your doing is squeezing the margins on the oil companies, think about this theoretically if stopping the pipeline stopped the tar sands (which it doesnt) then where does the remaining oil we need every day come out of the ground, maybe in the arctic wildlife areas obama blocked and said we couldnt drill at...... The oil is coming out of the ground regardless until the price of green energy comes down enough to match the price of oil.