The way I read the report, all the factors point to a classic case of somatogravic illusion. Fatigue provides an additional hole in the cheese, with rational thought being pushed back and gut instinct taking over.
I didn't see the interim report mention it, but I think the reported "do not worry" from the PNF may have referred to the PFs perception of excess pitch up. The subsequent "don't do that!" from the PNF refer to the PFs actions in applying ND trim.