Double back: I have had the 'mandatory' wave off at 50'. It is a TR training item. It is briefed in advance, but not warned of. It was rarely repeated in training afterwards. In LVO training the 50' G/A using autopilot is a trained manoeuvre. The a/c may bounce but the automatics do not. That's the education.
What has never been done is a G/A after touchdown. That's the training I'm calling for. It's a possibility & reality, so why not trained for.