I think he's pointing out that we have cold and arid environments with a standard atmosphere and surface gravity, and a magnetosphere to deflect cosmic rays tha

I think he's pointing out that we have cold and arid environments with a standard atmosphere and surface gravity, and a magnetosphere to deflect cosmic rays that we don't colonize right here on Earth. Traveling millions of miles at huge expense to try this on Mars doesn't seem like a sensible endeavor right now regardless of its feasibility.