If you're at a party, there's likely to be alcohol being served. And the kid is nude. Voluntarily or not, we can all agree that being out in public nude is not normal behavior.
Also, nude beaches, are reserved spaces. They're not like normal public space.
So the kid is violating public decency laws. And, the adults are just carrying on, carrying on.
Contributing to the delinquency of a minor.
Good samaritan laws. That might be a stretch, but it's arguable.
Depending on who brought the minor and why and what that party is for (is it a political fund raising party?), you could also be looking at a whole host of things too that might also have RICO violations to them.
I grant you, we'd need to look into them and we need more specifics.
But shit fire. When you see smoke, you outta have enough sense to look for that fire.
I'm not pretending I'm familiar enough with Florida state law to be lay out every single possible legal jeopardy here, even having had lived there. I also didn't have children there.
But your casual dismissal is somewhat concerning, because I doubt, being from Australia, that you're an expert on Florida state law or US Federal law specifically regarding minors either.
The reality of your comment is a "nobody cares about sex crimes or abuse enough to even bother looking when there's clearly smoke that needs and abso-fucking-lutely wants some scrutiny".
We see you sir.
That girl matters too.