The question we need to answer is, given infinite labor (limited over time, but unlimited given unlimited time) is there infinite meaningful work that a government can allocate it to? Eventually you will have built all the dams, tunnels, and bridges that you can usefully build. Historically what tends to happen is that work that isn't strictly necessary gets allocated. Roads that are fine get repaved, etc. I don't see how needlessly wasting energy and resources is better than paying people to spend their time however they see fit.