I have used this website during the era of Liberty Reserve (LR), they are Russian based company and they are legit then though i cannot say much about them for now, why not try them with small amount?
Trying with small amount then he get paid, it does not guarantee that he will get paid for big amount. So its better to find better information about the site with valid proofs before trying. As he knew this site from a lender, so I think he need to ask the lender to proof that the site is still legit till now.