I gotta be completely honest if my kid bothered to put this presentation, this much effort into convincing me, and I already knew his level of maturity to violence/sex from watching certain R rated movies with him and gauging how he reacts, and possibly see how he does in school, I'd consider it and probably get it for him
My parents got me the games when I was a kid without ever thinking twice about it and I warned them beforehand they were for 18+. I was also like 13 when they got me the GTA collection for the original xbox.
The result was that I played the games and nothing happened to my mental health.