What did Danny and Amos have a serious argument about shortly before Amos' cancer diagnosis as noted in the nonfiction book, The Undoing Project?

When Gerd Gigerenzer, a German psychologist, published papers criticizing Danny and Amos' theorie, Amos was angry about the criticism and wished to write a fierce rebuttal. Danny, however, didn't see it as a priority and strongly disliked working on the rebuttal, leading to a serious argument with Amos shortly before he was diagnosed with cancer.