No that wouldn't work because during a prop overspeed its the airflow that is driving the engine. The problem is with the propellers malfunctioning in a low pitch position - shutting down the engine would have no effect on the propeller pitch and the overspeed would remain.
As per the manufacturer/aircraft QRH, the only way to feather the prop in this situation is manually via the condition levers. If this doesn't work, the next option you have is the electrical feather pump which is activated via a switch on the overhead panel when the Np is <120%. This is hard to do when the Np during an overspeed can be in excess of 140%.