Another approach that probably wouldn't go down too well with insurance, but it's the sort of thing my teacher might do is as follows.
1. use him for demonstrations every time.
2. If he doesn't give you a decent attack, call him out on it. Make him practice his attack in front of the class until he attacks you properly.
3. Once he attacks you properly, POUND HIM INTO THE MAT repeatedly, without regard to whether or not he can take the fall. (He is wearing a black belt, he SHOULD be able to take the fall).
4. Rinse and repeat