Of course it's really a dumb move if he's forcing to gamble while his country got banned.
But if it's about ISP problem and then there's no other way except using VPN. I think every successful casino should have a mirror link, this will solve ISP problem and there's no reason to use VPN except they want to hide his location which surely a red flag for casino.
People from banned country are also interested in playing games but yes it's against the rules and should be avoided at any cost as if you are found using VPN to access the casino games your account could be freezed with the funds in them.
There are some mirror links provided by the team sometimes but many people still prefer these VPN to have some privacy also even if they come from allowed regions.