I think professor realized that we have free will within boundaries. We can choose, but we can't choose to teleport, or to be werewolves—those things are impossible. Hence you could have a heaven where people do have some choice, but not the choice to do harm.
Why did God give us the option of harm to see whether we should go to the place where we can't harm? That doesn't make sense.
Why did God give us the option of harm to see whether we should go to the place where we can't harm? That doesn't make sense.