Mahon wasn't being crotchety
Page 158 Mahon wasn't being crotchety. He was defending the view of the act of creation that would be codified four decades later in Andy Clark's theory of the extended mind. Writing about this very episode, Clarke argues that indeed, Feman was actually thinking on the paper. The loop through pen and paper is part of the physical machinery, responsible for the shape of the flow of thoughts and ideas that we take, nonetheless to be distinctively those of Richard Feman
— from The Mind in the Cockpit · Extended mind by Anne Murphy paul