Site admins don't care they'll give you the copypasta about how they're doing everything they can, they'll then ignore your suggestion and close the thread. I honestly hope something happens that gets them sued. Usually negligence is only solved in such a manner.
1: ban vpns so people can’t get around ip bans. However, some people may dislike this, so there is another solution.
2: either make all images blurry until clicked on or make a setting that does basically the same thing. This way, when this troll posts nsfw content, you can tell from the very blurry image that it isn’t something you wanna look at, and never have to see it fully.