Mirroring sites are a big help when a website like this one has problems. Using a VPN should really be the last option if the website has issues. Otherwise,
using a VPN could even end up being a problem for the gamblers who use it.
So, it's still a high risk to use one, even if a casino says it's okay. It's better and safer not to try a VPN at all, even for a short while,
if it could lead to problems in the end.
I will not risk myself using a VPN if the site can not state clearly that it is secure. I am worried about the problem that can occur later. So yes, trying mirror sites will be a good choice to try.
Maybe he can ask for the details and have a conversation with the support agents so he can clear everything and not make a mistake in the future.
One time I could not visit Betfury, but I tried using Betfury.so, and no problem at all. So you can see that mirror site help me to access Betfury.