The author says this knowledge can’t be extracted or transcribed, but isn’t that exactly what that senior engineer does after that hour has passed?

No. When we communicate, we're not really communicating our knowledge or understanding, we're communicating a crystallization of it in a form the listener might be able to learn from. The communication and the understanding are fundamentally different things. Like a map to the terrain. If they were the same, would we not be able to understand something purely by hearing it?