He isn't saying typing is a bottleneck, read the actual paragraph under the poorly written header. He is saying hunt-and-peck is terrible for productive flow and thinking and that touch-typing is important and valuable.

Even when pairing and taking time to think, obtusely slow typing from a partner is frustrating and distracting for me. If someone can't be bothered to learn how to use their tools well, they should find something to do they actually want to be good at.