Hi Karin,
Sometimes, we add a password to the Review 360 link that way they cannot access that link without it: https://community.articulate.com/series/review-360/articles/how-content-owners-manage-projects-in-review-360#share-projects
Other times, we disable the comments so they're not able to make more comments. They'll still see the course, but comments will be disabled: https://community.articulate.com/series/review-360/articles/how-content-owners-manage-projects-in-review-360#disable-comments
I hope that helps!
Stefanie