Betfair may be a desirable gambling platform to play on for you but if your region is restricted then you should forget about it and move on to reputable gambling sites without restriction, if you use a VPN you will still run into trouble in the long run. It's better to stay away than risking your account and funds by bypassing restrictions with the help of a VPN.
At least, he can ask the support system if their site allows using VPN and will not have a problem cash out the win money if he wins. By doing that, he can get the right answer from them to decide whether to use VPN or search for other reputable gambling sites. But move on to the other gambling site that does not require too many things will be better if he does not have any problems in the future. Many gambling sites are out there or from this forum so he does not have to feel difficult to search for the right site.
I'm currently experiencing the same thing, but with the risk involved, I decided to switch to another site and let a few small dollars sink in there. I initially tried to use a VPN and it wasn't good at all just because for the sake of playing there I broke the rules. I realized that at that time I was just trying to be as effective as playing at Betfair. Now I am more concerned about security in the future and enter a gambling site that allows our country to gamble.
If that is related to our country's rule, maybe it will be okay for now, but not sure in the future because the government can change their rule easily and the casino will change the rule too. Sometimes I use VPN and so far, I do not have a problem because I do not gamble for money. If I break the rule incidentally, I only use small money on the site so if that money is lost, and I do not mind. Talking about security, we need to protect the account, especially when we have some balance.