I'm interested to hear the response to this too, as I raised an issue about students being able to see a list of all courses within the system some time ago and was told that an update was being prepared that would split course lists into 'My Courses' and 'All Courses', with the ability to hide the new 'All Courses' page from students. Not sure if this would have resolved your issue, but even restricting a view down to category level would really help.