Correct me if I'm wrong, but breaking the EULA does NOT make an action illegal. It puts you in breach with an agreement you had with Blizzard, so they could terminate your account. But that doesn't make it a law. Blizzard may have some means to enforce the "contract" in civil court, though.
The difficulty comes in when the only use of the account, which would consist of the username and password, would be to log into Blizzard's servers, and since the account has been sold, it would be doing so in violation of the EULA and thus accessing their servers and circumventing a login without protection. This can possibly be a federal crime (there are a few cases tried as such, though it is rare).
So while the item being sold isn't illegal, it is pretty close to have no legal uses.
That said, I rather paypal (or any other business) not be the arbiter of law.
