Google and Facebook, which Gelernter says the very best people go to, have interview processes that filter out people who don't have a good command of fundamental topics taught in formal computer science college programs. Presumably the people who get into Google or Facebook are also passionate and self-motivated, most likely from an early age.

That implies to me that the self-taught+formally-trained people are in high demand and paid accordingly. Thus, Gelernter gets to choose among the people who are only self-taught or only formally-trained, and his sweeping viewpoints are based on his experiences with a subset of the workforce.