And who's reporting to law enforcement whatnow?
"yes, hello, officer, I'd like to report a party listing in a video game that's claiming to be 18+... What's that? Why are you laughing??"
My experience, cops won't do shit. My nephew was being molested by a neighbor and they didn't do shit about that. Go look at the problem in the UK with grooming gangs.
You're worried about what ifs in a video game when there's more important shit actually going on in the world and parents are effing clueless because they can't be arsed to supervise their kids. And social media is more dangerous to this than the game is.
You're singling out a problem that's really tiny in the grand scheme of things, and even if they made it fully against terms of service, who's going to report? Just listing 18+ isn't enough for a ban. And if you have access to someone's private chat, that means you're a guilty participant.