it comes down to proveing that someone is doing it. theres no way in the game that i know of to mesure if someone is useing a mouse and keyboard on the consoles
so it comes down to proof and without any. there hands are tied. and it turns into a he said she said type thing. if you cant prove someone is doing it. then you cant punish them for doing it. and also as i said above. theres no hard rule agenst it. if you look over the terms and agreements and all that fun legal stuff that the games make you read and understand .it does not say anywhere that a console player has to use just a controler. it would be like telling a PC player they could only use mouse and keyboard (( most of us do becuse again controler inputs are slower then M&K inputs ))