The only way I can think of to do this would be to prevent your instructors from add/edit/deleting ANY content, but that is probably too excessive for most use cases.
It's possible there may be something to help you with this interesting use case in the Master Course model, which hopefully will be released later this year.
Were you able to find an answer to your question? I am going to go ahead and mark this question as answered because there hasn't been any more activity in a while so I assume that you have the information that you need. If you still have a question about this or if you have information that you would like to share with the community, by all means, please do come back and leave a comment.