George wrote in favor of self-replicating space probes modifying the galaxy. George's predictions for the future are not consistent. A tiny fraction of Dyson Sphere capabilities or self-replicating probe technology would make Mars colonization trivial.
The "no human colonization of Mars" will likely end up getting retracted if George Dvorsky and Gizmodo are still around in 10-40 years. The NY Times had to famously retract a 1920 article mocking Goddard and his early rockets. The NY Times retracted the 1920 article about the dismissed the notion that a rocket could function in a vacuum after the 1969 moon landing.
George notes the lower gravity and atmospheric pressure that is 140 times less than on Earth. He also notes the extreme temperature ranges.
George says he believes humans will eventually visit Mars and even build a base or two, the notion that we'll soon set up colonies inhabited by hundreds or thousands of people is pure nonsense, and an unmitigated denial of the tremendous challenges posed by such a prospect.