I also noticed that a similar strange thing happens when trying to add a comment to the approved Revenue Cycle Model. If you try to save the comment, the Revenue Model name is highlighted with a red underline and when you hover the mouse pointer over it, the "Model cannot be changed as it is not a draft" error message is displayed. If you have a draft open, you can edit and save the comment. However if you edit and cancel the comment, the same behavior that I originally described occurs.
I wouldn't think that you should have to have the revenue model in draft mode to be able to update the comment (or the title).