212man and SASless,
The response to engine failure is often governed by the engine fuel control, which limits all paramenters to assure that the rotor droop occurrs, but that the engine is not harmed during that event. Thus the pilot has to use the lever to hold Nr properly, and all is right with the aircraft. With this engine limit protection scheme, no autopilot or pilot intervention is needed to assure protecting the engine, and the pilot does not have to fly using a combination of two gages, (the first limit gage and the Nr gage.) The fly away task is simply "make sure the rotor droops, and hold it to about a 2% droop." In other words, the engine limiter makes less workload than the first limit gage.
To rely on an autopilot to protect the engine is to have said "the job is too colplex for the pilot, so he must keep his hands off". This might be necessary at some time in the future, but is not needed now.