As one who has not had this happen, I can only guess. Maybe this thread should go to a forum with some fixed wing types can jump in and maybe you can find someone whos Prop went south...
I am guessing, that Yes CG will change but not that much. Also that he was probably in a climb and the engine RPM may have gone through the roof until the throttle was pulled back a bit.
Im sure some here will crunch the numbers for you.
I think the aircraft could be brought down to a walk away situation. In this case it was more than likely the landing area which caused the fatalities. That has not been mentioned. Maybe someone can fill us in.