I wouldn’t have to blame the casinos  totally because some of them made their rules very obvious and some of them also states that, they have the full right to withhold our funds the moment they suspect any criminal activities which simply means that, they have the right to investigate source of funds and funds record on your account for whatever reason that seems like scam to them.
I’m glad he got this money and the customer support to me was tactical in his mode of asking questions because he wanted to confuse your friend which he didn’t succeed and if your fiend was guilty of multiple accounts, he might be sanctioned if he accepted to having other accounts.
This tells us to be always very careful when responding to sensitive questions especially if we’re not sure of the questions or answers.