There's actually a user that has petitioned to become the first demerit source for exactly what you are proposing. More can be read here :
https://bitcointalk.org/index.php?topic=5033455.0Essentially though, if negative merit were implemented I do not believe that every user would receive an amount as we did with merit and sMerit; probably best to limit that to a small group of users that are extremely unlikely to abuse it.