My wife & I have an 18-year-old son. He started university in September, studying medicine. There he met this 41-year-old man - a classmate, and they became really good friends. This man has just started university now at this age because apparently he was born poor and in the first half of his life was focused on making money, but medicine is a dream of his. Son has always been an introverted, shy, socially awkward kid with little friends, but now goes out often. Honestly my wife & I are uncomfortable, and we can’t help but side eye the dude.
I used to play Star Wars 4th Edition Pen and Paper RPG with a 40 year old and his 32 year old wife when I was 16. They were just harmless geeks, like me.
If anything, my mom making snarky comments about the 40 year old guy really soured our relationship for a while. My friend who was my age and who also played with us sent her a picture in the mail of the 3 of us holding hands under a rainbow. She was pissed.
It’s fine. Your son could just as easily be friends with someone his age that’s a psychopath. It’s in the person, not the age. At 18 you’re going to have to trust his judgement a little more.