That is an interesting one. I wondered if you could leverage the Mute function in some way rather than Unlisting? The only one I can come up with so far is applying a default muted tag to the topic to remove it from people’s latest list, coupled with adding that particular tag to a tag group to make it only usable and visible to staff. Though adding the tag to the topic would leave a mysterious edit pencil where the history would show no change.
Having a button in the topic wrench to ‘mute for everyone apart from OP’ might be useful though.