To the OP's question:
I'd say that depends on when and how the helicopter instructor becomes incapacitated. My very first flight had me on the controls, en-route, going 60 kn. That way pitch or rpm didn't need much attention, pedals are irrelevant, and one is introduced to the cyclic and its operation, accompanied by the instruction that "we don't climb or descend using the cyclic like a plane uses its elevator but only by adjusting pitch". I actually was given that piece of information right during my first 10 secs at "some" the controls.
Now if my instructor would have fainted at that point of our flight
AND would have fallen over towards the door's side
AND would not have crumpled over the cyclic,
I'd be in panic, probably talking to the airfield's tower, hoping the flight schools boss might be within reach.
The only way I could imagine to have landed the thing would have been airplane stlye e.g. w/o hover:
Suuuper long final, very low, still doing the 60 kn I already encountered.
Hopefully gradually lowering pitch and doing a 60 kn screeching landing right onto the 3000ft tarmac.
Would I have known to avoid low airspeeds (as I wasn't able to hover, back then)?
Would I have known to avoid the grass for such a high speed "landing"?
Probably not. But I think a helicopter with skids can be landed safely as describe even by a 0 h "pilot" .
However would the instructor have fainted during takeoff or landing,
would he have sunk over the controls, maybe pushing down the pitch in the process, I'd be toast, for sure.
does this sound right or am I misjudging 0 h pilot's skills ?