Perhaps Trump should have ended US support of the Keystone project like Biden has in that case. Maybe Trump craved more popularity from Canadians as his reason for supporting Keystone. I suppose that Biden, the most popular President ever elected in history has no such motivation or interest in the Canadian economy. Congrats?
Or maybe Trump supported it as a small part of his attempts to destroy the USA? Maybe Don Jnr was going to pick up a fat consultancy fee and split it with dad? The only thing you can be sure of is that Trump did it because it served his own interests and not those of the USA.