The behavior of the slime mold (if that’s what it is) sounds altogether too modern for Dr. Cohen’s liking. That’s understandable. See, for example, “Is an amoeba smarter than your computer? (yes, in certain respects, it is) The trouble is, many forms of behaviour, like nest-sharing and parental care, have been found earlier than expected. We shall see.
We’ve often heard that there were billions of boring years in the history of life (the Boring Billion). Maybe not so boring.
The microbes that metabolized practically anything back then just to stay alive didn’t appear to want to do much else. Yes, it’s an old question why they didn’t (couldn’t?) Or maybe they even did. But based on the history of the last half-billion years, there should be an answer.