I'm no doctor, but according to this, he's actually worse than your average 8-year-old.
Important aspects from the link above:
In conclusion, I genuinely think Kevin is more developmentally stunted than a child just entering pubescence.
Ok let's see:
Learn to cooperate in group settings and group games; dislike playing alone-We've seen nothing in terms of his ability to work in a group in an educational/ work setting. But using what we do know to about how he contributes to running the troon ranch, it doesn't look good on him. He does nothing beyond giving some of his NEET bucks/ inheritance on the troon ranch. He doesn't do chores, doesn't help look after the animals, and doesn't clean up after himself. It appears he's unwilling to help with physical work due to how lazy he is.
Use problem-solving, negotiating and compromising skills with peers: Hasn't shown any of these skills in a practical sense. If we're going on how he handles descending opinions, Kev-Kev has a "my way or the highway" attitude which isn't a good sign for negotiating and compromising skills.
Develop interest in long-range projects: Hasn't shown any interest working anything for any period of time. If we're going on his finical management skills, Kevin doesn't really think about the long term. Closeting thing that comes to mind is that he constantly shills the troon ranches gofundme.
Begin to develop sportsmanship and learn about winning and losing gracefully- No particular instances of Kevin competing in a sport or game come to mind. But if we're going of his political takes and what political happenings are considered a "win" or "loss" for troons, again, not looking good for Kev. The most notable instance of Kev not handling a losing situation would be him ranting about he thinks that
conservatives don't deserve rights after ACB got appointed to the supreme court.
Develop competence in competitive games and team sports: No samples of him competing in a game or sport so can't really comment here.
Become sensitive to what others think of them and to adult approval- Posts whatever degenerate shit he feels like posting, openly e-begs, openly brags about wasting his NEET and scam bucks on toys, vidya, Onlyfans and other worthless shit. He posts gross shit and openly acts like a child.
Become enthusiastic to tackle anything and will work hard to develop a skill- Kevin has no ambition to improve himself or even be employable. The closest thing him developing a skill I can think of him wanting to get better a video game.
Develop competitiveness—want to be first and best, and get things right- Kevin has basically no ambition when it comes to being an adult or being a professional in anything. Again, closeting thing I can think of for this is vidya.
Show interest in being more grown-up and able to begin tackling more responsibilities and routines- Doesn't exhibit any of these in any sense of context. He lives his life like a child.
In short, he doesn't have any of these traits and I was way too generous comparing him to an 8-year-old.