I don't think what we simulate in training by jamming a pedal is exactly what happens when the tail rotor comes off or stops. The spinning disk will still provide some "keel" or effective fin area. What you do in training is try to impart the correct reaction on the pilots so that they have some idea what to do. Let's face it, in your career as a helicopter pilot you will likely face a loss of tailrotor situation, maybe several times - nothing to die over.
Just like in an auto landing when the blades suddenly lose all lift when the NR gets below that magic number you can get an idea of the same for loss of tail rotor. Fly along at 60-80 knots and slowly push in full pedal (in the direction of the main rotor rotation) to approximate zero thrust. When you are at the stop, start slowing down keeping level. At that magic airspeed the tail finally lets go and starts to whip around in a spin. To finish off the exercise we used to let it spin a couple of times and then chop the throttle and auto to the ground without ever moving the pedal off the stop, but you needed some altitude to get it to work out