I came to the conclusion some years ago that the huge majority of the training value in an auto stops at the end of the flare. If Bloggs can safely enter auto, turn into wind, look for and find a suitable spot, adjust the flight path to make it to the spot (or if he can't make that one, pick an achievable spot), make a radio call, warn the pax, arrive at "the gate" with the right airspeed and the right RRPM, and flare the bird to make the spot, he satisfies all the requirements.
Actually plonking onto the ground need only be done a couple of times to demonstrate the experience. In real life, sadly, what is under your skids at the end of the flare is unlikely to be a flat, hard surface. A run-on might end up in tears.
So, a power termination is a suitable ending for the exercise. Especially at night.