Hi Cam...
You are absolutely correct. In the case of that particular Enstrom, the
engine lost power and the clutch didn't disengage. So, the airflow upward
through the rotor which should have been retaining the rotor's autorotation
R.P.M..was expended trying to turn the engine due to the NOT disengaged
clutch. The situation was bad anyway because they didn't have much
altitude- maybe a couple of hunderd feet.