Yes, except that if the Constitution says it is allowed, you can't make a law at a lower level saying it's not. Any law that contradicts the Constitution is by definition illegal. The only exception to this are gray areas such as gun control, where as long as the people have access to any guns, legally you can still target and ban guns, just not all guns, with the level of support for what type of guns are allowed being determined primarily by the population where the laws are written.

So effectively, if it's federally, state, or otherwise owned, slave labor in prison is allowed. The state can make it a policy to remove it from state-run prisons and potentially get away with it, but that's a soft policy more so than a hard ban and any other entity working in the state for running prisons must be allowed to have slave labor be available as an option for them otherwise Colorado would be breaking Constitutional law.

That's how the law should be interpreted, and that's why I consider any "abolishment" of prison slavery at the state level to be a good first step, but largely impotent.