I'm saying he probably wouldn't like it, not that he's incapable. Of course Ubuntu can do everything he would want it to, but it wouldn't be as simple an experience. iTunes would be a pain, LibreOffice sucks, and gaming isn't as good.
If there's a problem, and there will probably be something, having to jump into the command-line for a non-technical user isn't good. Not everyone has a you or I around to help them, they just want everything to work.
Yeah, I get what you say, but his expactations for his OS don't include gaming, maybe just a bit of it, but I agree that if he does want to play, it would be a real pain in the ass to get it going on Ubuntu. I Tunes would be manageable I presume.
And as I said, if you install it correctly and he won't change his expectations any time soon, Ubuntu can work for him. And then, when he needs to install something new, it is not as hard as you portray it to be. There is Ubuntu SW Center, most things you can do right from there.
And also, you are saying that Windows has absolutely no issues ? No problems will occur ? I switched to Ubuntu because of Windows having too many issues, I spent too much time fixing shit and adjusting it to my needs.