I persume that your registered your own name, trading as ps3? If so, you are a sole trader and hence have unlimited liability to the "business" in question. Guess what happens if sony sues you and you lose... bye bye house!
Ah, that's probably a real worse case scenario but it is possible. More likely as a scare tactic on their part if they really want the domain. What's the point of the rules of the
IEDR if you follow them and still get caught out