You can try to get the account banned, saying it was a purchased account ect ect, they will ban/suspend/lock the account. All he would need to do is call in and verify the information that it is his account.
I had run into a scammer on PA who bought an account, it was delivered, he said it wasn't to his liking and PA gave him his money back while I was out of an account. Well, he xfered the toon off the account, server and named changed (PA told me too bad, but since I was the original owner I should be able to get it back).
Since I wasn't about to let myself get scammed I called sony, said I logged onto the account and my toon was gone ect ect. I verified the info on the account and they reversed the transfer within 10 mins. Well the guy who tried to scam me called in sony and got the account "banned/suspended" or locked, whatever it was. All I had to do is call into sony again, verify original owner info and they opened the account back up right away.
I'm not sure if anyone else knows a way to get an account perma banned but just telling them that it was a sold account will only get it locked until he verifies ownership.
Now, if I'm ever looking for an account the only place I have any trust in is here.