In some states/countries age of consent is 16 and they didn’t really have sex. But I agree with you he isn’t old enough for many things. And co-sleeping, cuddling, hand holding with a minor problem could be seen as grooming/molesting intentional or unintentional. It’s a slippery slope. Even if age of concent is 16, if the other person is 21, there is already huge imbalance in maturity level