Suppress category but keep topic for OP

I’m not clear on what you have on mind, but here’s my rough explanations.

There are Group level permissions that are central. Discourse does well at advancing members’ trust level group.

A member has preference settings, among others, for watching - tracking - normal - mute, for categories, topics and tags. In combination with notification and email settings members can adjust how a forum “gets” to them.

Categories have additive permission settings for Groups, i.e.

  1. Create - Reply - See
  2. Reply - See
  3. See

Note that some options are not available, but if you create a plugin (or maybe a pull request) I think at least a few others might use it.

The Staff group has extended privileges and Admins can do anything they want to do.

So, background done -

What you could do now without touching any code is:

  1. create eg. a “membername_group”
  2. add the member to the group
  3. create eg. a "membername_category
  4. give the category “everyone” group See permissions and
    “membername_group” See, Reply [Create] permissions

- or - you could use the message system. Moderators have extended privileges so there would be no need to worry about them Seeing as long as it’s started from Flag - Other