The penny drops, I think. Well done, TTO.
18-Wheeler,
No. The engines are normally working at over 90% in the cruise, and the forward thrust at that power setting is hardly worth diddly squat. If it were possible to decouple the engine from the main rotors, by the time you had reached a point where the engines were wrecked due to overspeeding, you'd still have only diddly squat and a bit of forward thrust.
By that time anyway, the overspeed protection would have hopefully done its job and shut down the engine.