The definition of a meta tag from SO's Tag Privileges is:
Tags that cannot stand alone as the only tag on a question
The negative tag has no followers, no tag wiki, and multiple questions tagged with a specific language that is being asked about.
It seems that it would be pretty hard to create a question tagged with just negative. Of course it's possible for somebody to come up with an example question that would be suitable for being solely tagged negative.
But is catering to that minute amount of questions really worth users improperly tagging their questions? What does the negative really tell us about a question that couldn't be determined from just reading the question?