Sounds exactly like a Class 1 heli-pad approach as specified in the AFM.
I fly the 135 and our ops manual says that ALL approaches to confined areas shall be flown to the Class 1 profile (EC135 LDP 120' IAS 30kt ROD less than 400' per min) In the event of an engine failure after LDP the landing even at RTOW is assured. The take off is basically the same thing in reverse (TDP 120 ft, ROC 200-300' FPM keeping the landing area in sight at all times)
I can understand why your instructors bark when you try it, if your'e in a single engine aircraft it will stick you (and the long suffering instructor) right in the avoid curve, while a lot of utility pilots spend a lot of time in the avoid curve many instructors are a tad concerned at being in the curve with a low hours student in control, an engine failure there will pretty much guarantee a broken helicopter and occupants.
VH