I was wondering if there is a possibility to hide a specific topic from the Solutions tree from a group of specific people (not end users, but technicians - so Self-Service portal is not an option)

 I want to keep there only "Retired" solutions and/or drafts that should be checked by admins only (I know we can keep those under the Unapproved status but my main concern is keeping the Solutions results as small and as possible, with minimum results)

As a workaround I tried to delete all keywords from these solutions to test if those will still disappear but they still do...

I guess I should create a restriction for a specific group, as described here but I am not sure how 

This restriction should be an automation done per Solution topic - is there a way to make this work?

Thank you,

Laura