Roblox in particular has been super hostile to the Linux community, they've two or three times now intentionally changed their application to make it so it won't run under wine. If Roblox is something that is a hard requirement for him, I would highly recommend against any of the non-windows derivatives. The lead development team on Roblox seems to have the ideology that anything that isn't Windows is a hacker platform and therefore they attempt to remove access from those platforms wherever possible. I don't personally agree with it but, it is what it is.

I also wish people would stop blindly recommending Unix platforms as a drop-in replacement for gaming on Windows. I have yet to see anyone who has been able to just install any of the flavors and have it "just work". I fully agree that we are ages better in terms of compatibility than it was even 5 years ago, but at 100% should be going into it as a "you will have issues prepare to have to troubleshoot" and if this was his first time using anything not windows, I would have hard recommended against nuking the windows install, at the very least shrink the C partition on Windows which can be done via GParted, which thankfully is already pre-installed on the Linux Mint installation media.

It's disappointing that he is looking to go back, but I can fully understand his frustration, as someone who's recently retaking the plunge after 6 or 7 years of being on windows again, I find myself getting aggravated at times trying to make hack scripts to make things work as well.

That being said, if he is wanting to go back you shouldn't force using it, that's only going to remove the possibility of him switching back in the future(like when MS makes w10 a subscription model either end of this year or the year after which will force w11)