I have promoted porn for nearly 2 decades and have seen the laws analyzed inside and out (by others). What you say is true.

What is also true is this:

1) You have to report potential child porn to authorities when someone notifies you of it, even as a service provider.

2) Figuring out if a nude picture of a minor is sexual is not something I would ever want to be responsible for so I'd err on the side of caution.

3) Most importantly - The minute you collect all of these pictures in a sub that uses the phrase jailbait and have users commenting on how they want to fuck them or similar you are now allowing the sexualization of minors.

I am a free speech advocate through and through. I was publishing porn in small town Christian USA back when everything was a gray area and the feds were shutting down porn shops just down the road from me for having Hustler Barely Legal videos. I have been there for goatse, lemonparty, tubgirl, the beheading videos, and every other "shocking" thing posted online. I have had in depth discussions with people that ran bestiality and scat sites and regardless of how I feel about the content I want the laws to allow them to stay online.

In this case I would nuke those offending subs from orbit and so would anyone else that planned to legitimately run a social platform like VOAT. It simply won't survive without taking action against this stuff.

In the Rolling Stone article on 4chan you will find this.

Poole has never had any employees. Instead, a couple of dozen volunteers around the world monitor threads, kept discussions on topic and removed snuff films, child porn and other illegal content.

Even the lawless land of 4chan removed illegal content, for reasons.