His ideas have to be taken seriously. He's qualified, and certainly credible. That said, they spent an inordinate amount of time discussing his theory giving off the impression that his theory is far more prevalent in scientific research than it actually is, especially since they had no real discussion of alternatives, such as the dominating model (String theory), loop quantum gravity, or other less accepted theories. As far as him being young, I think that's irrelevant. The work Newton did at 23 is now legendary, and Einstein published his theory of relativity at just 26.