Don't you think some kind of trusted "post curator" list (or something similar) is worth exploring?
Maybe if it was made up of a few selected users rather than just anyone with "greater than x merit" which is easily abused, but then that raises the question "Why not just appoint said users as moderators"?
and negative trust could be used as a tool to combat abusers?
This would not be a good use of the trust system.