This is a weak argument. I agree there there is a lot of value in stepping away from a problem to give your brain time to chew on it. That said, filling every moment with busy work doesn't produce these results nearly as well for me as taking a walk.

We need to get away from the idea that need to pretend to be actively working on something all the time. There is value in the white space between tasks, and we don't need to pretend to be working on boring nonsense. It's knowledge work, thinking is part of the work. Why do we have to look like we are doing something productive while thinking? It's all performative.