Set a specific category to be private by default
I am trying to make a specific category private by default. I am administrating a website for a medium sized artistic community and would like my users to be able to publish private posts, through a front-end plugin I have elected (User Submitted Posts). They can chose in the front-end form between various categories for the post they are about to publish (that i have selected in the back-end), some should be public (news/exhibition announcements), whereas others should be private for internal exchange only (for example sharing equipment, asking a favor, etc…).
Is it possible to create a function that would be affected to a category (by ID or slug I suppose) ? I have found some code that applies to custom post types, and might be adaptable to a category ( Set posts of a custom post type to be private by default?), but I am a total newbie with php code and do not want to mess with my functions without being sure of what I would be doing.
Thank you in advance.