OK you are coming back with your student, governor-off training, all goes well, correlator is making things easy. good approach, student start to taxi carefully, RRPM gets a bit low but ok, now student start to taxi down wind (only way to the pad), wind engages the tail, student puts full power pedal, lose more RRPM, buzzer is on, student get nervous, rotor lose more efficiency, AC harder to control, student crank a lot of throttle, MAP is now the red, rotor dangerously decayed and you are still flying. this situation could have happened. not necessarily a stunt.
Engine-off autorotation, same thing, in the last few seconds as you adjust your touch point, you will find yourself flying with the rotor decayed to its absolute limit of lift vs RRPM
For the technical reasoning, the factor that would deserve primary attention is the impact on the blades due to the reduced centrifugal forces if you assume that at nominal RPM the rotor can endure a maximum load factor of 2 to 3 at MTOW (ie a turn of 60 deg bank+) then the rotor should be able to assume a reduction of centrifugal force of 2 to 3 at MTOW or almost 4 at MTOW-30% (a lightly loaded AC) this translate into a reduction of RPM of 50% (square root of 4) not too far fetched.
I retain the disclaimer:
The normal and only practice is the flight manual that has been defined by much more qualified people this side thinking is a distraction that is keep very well separated.
Another point:
I think students are not exposed enough to low RRPM, yes they teach you to lower collective until it becomes a motor reflex but you will still find individuals doing the wrong thing or freezing or suffering brain fart when the buzzer is blaring and the rotor noise is lowering its pitch I could dare to assume that more exposure to this low RRPM condition can tech the brain that there is no reason to freeze.