As a citizen of Earth, I'm of mixed feelings. On the one hand heavy crude from the tar sands, which is some of the most polluting oil on the planet, because it requires so much energy to extract, will keep shipping by rail to the United States. That involves more spills than a pipeline and burning yet more fuel. That's bad.
On the other hand that makes the prices higher and both constrains the volume of output and the price at which it's profitable to extract. Both things that mean more of that tar sands oil will stay in the ground. That's good.
On the other, other hand - more tar sands oil staying in the ground means more oil from elsewhere in the world, often from politically unstable or unfriendly regimes will replace the oil the US otherwise would have imported from Canada. That's potentially bad.
I'm not sure which outcome is better for Canada, the USA, or the world. I'm pretty sure neither Obama, Trump, not Biden had any accurate idea either.
Edit: and the downvotes are because you disagree with my economic analysis? Or because you think any of those politicians actually have a solid, fundamental analysis including unintentional consequences? Get real, they did it for political reasons, that's why they came out on different sides of the issue based on party lines. Actually judging by the downvotes, I think it was a smart political move. I really wish HN would require a comment with a downvote, even if it's only visible to the OP.