Please consider adding site group permission to category administration. This would allow site groups to view or not view the category. Default would be to view. The use case is common products that are published in a number of categories but not all categories are to be seen by particular groups. For example, categories are setup for East and West. Many products are specific to one or the other. A few products should be available for all. I realize that a third category for the common products is an option but not what the end customer wants.