These discussions tend to always focus on the theoritical rather than the practical.
The HV curve is valid for both the take-off and landing/descent profiles. It is very, very conservative during descent and landing, but the curve remains valid nonetheless. The "recommended take-off profile" corridor works forwards or backwards, climbing or descending. take-off or landing.
The bottom line, real world result of an engine failure within the low speed avoid area of the HV curve during an approach to landing where the collective pitch angle is considerably less than that on a maximum power take-off is that the pilot will have a greater chance of landing without damage or injury.
Does any helicopter pilot really need a manufacturer to tell them that?