Well, I believe my recommendation is to give it a shot or to contact customer service.
I would refrain giving it a try. If he do something like what he's planning and the casino finds it out then there's more trouble to his money. It's better for him to talk seriously with the customer service and be outright on what has happened.
Things can be done peacefully if it's being made through talks and I think that the casino will spare him as it is his fund and didn't came from nowhere. There's a chance that he'll be given consideration.
The chance of getting the funds back with sincere talks with the customer rep is better if the site is a known reputable casino here.
But if not, high likely that the site will freeze his funds because he is using the site from prohibited countries.
The OP should also check the terms of the site regarding the use of VPN on the casino.
If the site is allowing VPN, then he has good hope to get the funds back even using his own credentials.
Because the problem with asking from a friend is that, it will suddenly give a different IP, which is very different from his previous recorded IPs.
Which will give the site more suspicion about his account. So for me, it is better to talk with the site about the real status of his account.