I was thinking about this and what if we just limited the amount of XP that a person could go down? It is highly unlikely someone who is serious would try to inch their way back into good graces from a score of -100 XP or so.

Lets say once they reach -100 XP they cannot go any lower. It would deny those individuals the enjoyment of getting a descending score.

If they did not care about XP and just wanted to troll then a cap would not anything to change their behavior, positively or negatively.