Puff
I think I found the Baron incident that you refer to. it's report 200000624. Unfortunately the ATSB do not publish the full report - only the synopsis.
In that case he had a dead engine, pure & simple and I think the simply "dead leg, dead engine, confirm with throttle" routine would have identified that.
In this case the engine was unquestionably delivering power. The engine was surging and probable the aircraft was yawing in response to the surges. As the engine surged it would have gone out of sync, so there would have been constantly changing beating as well. The question no one will be able to answer is whether there was a low power setting that would have stabilised the engine and delivered more power than the zero thrust setting.
In the early stages of the incident (before the RH engine was feathered) the desecnt rate was up to 1600 fpm without any corresponding speed increase. This suggests that the desecnt rate was caused by the drag of the mis behaving RH engine / yawing aircraft rather than poor airspeed / attitude control by the pilot.
I think shutting down the RH engine was a good decision. Whether or not it was the perfect decision can be debated for some time. Its interesting to note that my Seneca II POH does not have any reference to action for a mis behaving CSU. This would make me wonder if the Mojave POH is similarly deficient. Another thing the ATSB might have considered but did not.