He probably wants to play multiplayer. Multiplayer has other people in a lobby and it is actually fun and it's not really bad and disgusting either. The only bad things about it is if people start swearing in the mics and harass him.
He probably just wants to play with his friends from school or something like that.It's part of the school hierarchy to have games like these at least for the boy section. And think when you were in school and you really wanted something just to look cool and fit in with the other kids.It's called empathy. I would really recommend that you monitor his game play and tell him if he does something wrong on the game e.g. violence that you will take the game away.
Despite all that bad stuff, GTA can really be a fun game without violence, you can explore, race, pilot airplanes, skydive, go in the sea, make new friends online,have competition, and much more without ever shooting a gun! Especially monitor the single player as they have missions that have violence. But overall, it all depends on what you think.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.