Unfortunately, this suggestion, like so many other good ideas, requires programming resources.

It doesn't in a strict sense, establishing a protocol for this decisions to be enacted in comments is sufficient. Given a wiki page that describes the protocol and lists people authorized to vote, any of them can create a top-level comment with words "Vote to hide", link to the wiki page, and possibly an argument. Others can reply to the comment to second/third the suggestion. A rule such as ((Post Karma - (number of votes to hide) * 10) < -20, and Post Karma is less than 10) then decides whether a moderator bans the post. The whole voting thing can even be made invisible to non-moderators, if all comments in it are hidden right after being posted.