Because, IMO, he was about to say something (potentially) negative, so to counteract that, perhaps (?) Maybe he had his personal doubts? But who knows. He was party to material we are not, original statements etc. As you suggest, it rather jars, perhaps, this unusual praise. It’s interesting you noted it too. Not to cast aspersions on on CV/KH…
It’s interesting to see other points in the text where the edits might have been. Something unusually banal after something a bit more potentially salacious, a negative followed by an extreme positive. It feels almost as if a hint left in (?) It was a neutral, impartial take.