Flexshaft, basically no.
The ME avoid curve is derived from the H/V combination where a safe landing is not assured after losing one engine. I.e going from AEO to OEI. Nothing to do with autorotations.
Due to various torque/engine/pilot limitations you are not necessarily "safe single engine" in all phases of twin-engine flight.
As an example the Lynx which I flew typically had a minimum single engine level flight speed (MSELFS) of 0-50kts, depending on the environmental conditions and AUM. Flying below this speed at an altitude which did not allow a descent to increase speed to recover is inside the twin HV curve.
Hope this helps.