A37575, I would suggest that failing to confirm (but not necessarily by retarding the throttle) after deciding dead leg = dead engine, is not a good practice. A common trope with PT6 powered twins eg Kingairs, is 'dead leg = dead engine = dead pilot'.
PT6s have a single point failure in their fuel pump governor that will give an extreme runaway engine, with similar yaw characteristics to a failed engine. The difference is that the yaw is *towards* the GOOD engine. If you don't confirm the runaway (from torque, temp, & Ng gauges in this case) then you could feather & shutdown the *normally* functioning engine, with the remaining engine about to disintegrate.
Bear in mind that in this situation autofeather *will not* engage. You're left with an uncommanded yaw towards a properly functioning engine. Those dead foot = dead engine drills will kill you.