It sounds like this is limited to passive surfing. No permission is granted for publishing or purposely storing or redistributing it (so Facebook, a private company that can ban pictures of green dogs if it wishes, wouldn’t be embroiled in this), and probably not for subscribing to a service that specializes in it. And if it’s not actually made from children engaging in the acts depicted, it escapes sanctions anyhow, by a USSC decision of years ago from the Sandra Day O’Connor era — the point seemed to be that the only valid legal reason for such a ban was to prevent children from getting molested or exploited which would be inherent in making genuine child porn.
That doesn't sound like "passive" viewing to me.