What levels of drag and vibration on a 2-blade system and a delamination at the tip would be, one can only surmise but that extra drag would have decreased the Nr even if he had kept the engine going - without it running, perhaps because he panicked and assumed he had an engine problem, he had no chance of retaining Nr.
Good point. Vibe levels were undoubtedly dramatic. I had a mag go bad in a way that shifted the timing. That was dramatic enough, but I never thought about securing the engine while it was still making power.