I doubt most instructors would deliberately demonstrate a bounce, simply to protect the aircraft.
Then they shouldn't be instructors if they lack the competence to demonstrate a bounce. It doesn't have to be a huge aircraft wrecking bounce where nothing is learnt. A normal round-out and greaser touch down followed by gentle pull back on the stick to simulate over-controlling on the elevator to a few feet to simulate a bounce and then a touch of power to ease the aircraft back on the runway. What could be more simple? At least the student has now witnessed a controlled demonstration and knows what to aim for. It is not astronaut training and even the most inexperienced 250 hour grade 3 should be taught how to demonstrate the manoeuvre before being awarded his instructor rating. After all they are going to be witness to hundreds of bounces as instructors. Surely that is part and parcel of instructor course training? Or is it?