Things are rarely black and white. Most situations (and all people) are complex. A nuanced approach is necessary to understand them. You can’t learn - or love, if you’re judging.
Avoid commenting on the number of children someone has (or doesn’t have.) Its none of your business to ask why a couple doesn’t have kids or remark if they announce they’re pregnant with their 7th (other than to say “Congratulations.”)
“What do you think about keeping things PG-rated for a while? We’re both just figuring stuff out. The last thing I’d want to do is hurt you.” Or whatever spin you want to put on the idea that there’s no rush, and plenty of amazing sensations to experience and explore, long before things go further than kissing. Hang out in that PG range as long as possible. And if you can’t talk with your partner about that then you probably shouldn’t be having sex anyway.
Be present. Don’t turn every conversation into a lesson. They stay in their rooms so much because they feel safe there. They’re tired and stressed out and managing a lot of change.
Speaking truth to power is important but should be done carefully. Before you speak remember this: Is there anything self-serving, mean-spirited, or ego-driven? If you’re sure your feedback isn’t tinged with those things, then I’d say you can be comfortable telling it like it is. Note: when you’re young (less than 30) WAIT to be asked before you spill your guts! Always be kind, professional and consider what you want to say carefully.
Check out fencing. Local fencing club has classes for kids and adults all ages. They also do birthday parties, so that might be something different that would be fun for him and his friends.