Make CT work with/like Unitag

As asked here #300512: Tag approval queue? for 5.x, i believe there should be a way to approve/disapprove user tags to prevent spam and unappropriate tagging. Currently Unitag module provides this feature on node submissions for 5.x branch. It does this by making free-tagging vocabularies read-only and sending non-existent terms to a management interface where they can be dealt with either by

• saving as new terms,
• saving as synonyms of provided root terms,
• saving as child terms of provided parent terms,
• or deleting.

Unfortunately Unitag module doesn't work with the current implementation of CT and also there isn't a 6.x version. So even CT could be made work with Unitag, this won't help 6.x users. Perhaps it may be possible to implement this feature directly in CT instead of making it dependent on Unitag.

Btw, here is the Unitag maintainer's comment on the issue.