A recent discussion on the /loli/ board on 8Chan that I thought was interesting;
(Of course, this is all just a random discussion between anonymous users on an unreliable board, so take all of this with a giant grain of salt).
I really don't think there's a government agency involved in all of this; they would have gotten involved years ago, when the site was contacted by authorities and ended up hiding all the content behind a registration. Unless, of course, something particularly serious had happened that's being kept hidden.
What I find interesting is the discussion about "The Gray Zone". Personally, the only things I know about "TGZ" is what others have said: a safe haven for borderline pedophiles where they meet to discuss their sicko behavior, the kind of people for who "just a drawing" isn't enough. You know things are fucked up when even lolicons don't want to share a website with you.
While I have no sympathy for any of these people, there's no reason for anyone to platform borderline pedophilia. I hope it's true that Vistarrr is removing pro-TGZ supporters and eventually removes the entire section from the site. It's the least that could happen now that ATF will continue operating.