Laws which add costs to labor means that wages are going to be lower than if those costs weren't there. In a tight labor market that means employers have to go elsewhere, so more outsourcing or they cut back on labor employed. There is a reason why Europe has such high unemployment rates (and comparatively lower salaries) and struggles especially with youth employment. But they have much better worker protections. It's a tradeoff.
Now that doesn't mean it's not worth it to pass certain worker protections. But every such protection will have a cost in terms of reducing demand for labor. Maybe the cost is small and the benefit is high, in which case, go for it. But don't pretend that the costs aren't going to be paid if you federalize the law, or that there is some sort of legal arrangement you can make to outlaw economic tradeoffs. The costs will just be paid in a different way.
And it's not like everyone in Colorado is suddenly unemployed. Lots of people are hiring Colorado workers. It's just a small decrease in demand for Colorado labor in response to a small increase in employer headaches for hiring people in that state. If those who supported this law didn't expect exactly this to happen, then they were uninformed. I am assuming most people in Colorado knew this would happen and decided to pass the law anyway. Time will tell whether the benefits outweigh the costs, but there are always such tradeoffs.