This doesn’t seem to be the case any more - in my site, it seems to be admins only (discovered after attempting to coach one of my mods to convert a topic to public). I can’t find a setting that governs this.
Not sure if this is a regression or is deliberate.
Okay - I understand the issue now. It has to do with the interaction of deletion and changes to the admin menu of topics which don’t refresh until the page is reloaded. This is a bug (albeit it a very minor one).
To repro:
Visit an existing Topic (can be a PM) with an account with moderator/admin privileges
Delete the Topic
Note that the option to Make Public Topic / Make Personal Message remains visible
Refresh the page
Note that the option to Make Public Topic / Make Personal Message is no longer present
Undelete the Topic
the option to Make Public Topic / Make Personal Message remains absent until the page is refreshed
It seems like a page refresh is needed after deletion / undeletion of a topic. Perhaps this should be included in the action of topic deletion/undeletion?