Never heard of Rust, but it sounds like something I can afford to ignore.
OS shouldn’t even matter to prevent cheating; do your anticheat validation server side. Anyone who knows anything about security knows the client side can never be trusted.
I did recommend Mint (although I use EndeavourOS myself), but he’s not interested anymore.
It probably didn’t help that I recently recommended him to buy Nvidia rather than AMD for a recent upgrade, because Nvidia had lower power requirements, and I don’t his his PSU would have been able to handle the comparable AMD.
My son also picked Bazzite, which I hadn’t heard of before. Unfortunately he didn’t like it and it back to Windows again.
Oh, I’m very good at avoiding games like that.