The problem behind this is, you can´t ban or punish a player for just playing the game.
E.g. if you farm a heroics area (which I think he did) and every mob in there gives you 10 cxp (as it does for every champion mob or above), than you can´t punish the player for this reason.
Even if they maybe nerv maybe the amount of mobs in this area.
The whole thing looks a bit different if there is maybe on mob which gives you 100 cxp (which he is not intend to do so).
In this case you can ban players for exploiting, cause the used a mechanic which obvious is an exploit/Bug.
Calm down, and wait until the patch is over. If the will not do anything we have a nice little farming spot