There is still an appeal to the US Supreme Court that I didn't know about. So this is still in play.
Discussion
I've been thinking about this and I don't think the US Supreme Court should overturn this. Ballot access is a state issue. States vote for the president, not the people. If Colorado decides to exclude Donald Trump, that is a Colorado issue, not a United States issue. It is up to the people of Colorado as to how to react to this.
Having thought about it a bit more... the way Coloradians can fix this is to contact their local state legislature representative and ask them to appoint electors in such a way as to represent the popular vote for Trump, that is, to change the law so that this Colorado Supreme court decision becomes moot. States vote for presidents via their electoral college representatives, and they are chosen according to whatever the legislature decides. So the Colorado State legislature can effectively bypass the Colorado Supreme Court. And if that gets challenged, the US supreme court will enforce.
Colorado has become a blue state anyways so it's probably not relevant.