"The amount of electricity needed to power these technologies would be greater than the entire world’s electricity demand today"

This is where the argument falls off. For what its worth I think they are right in the sense that relying solely on carbon capture is bad economics, but having it in the mix makes a tonne of sense. I do expect carbon capture to become more efficient over time just as much as I expect energy to become more abundant, and part of that energy budget should go towards capturing the carbon output into the environment from legacy technologies.