The problem is, the moderator would need an accurate list of who is a book reader and who isn't. Zin claims he isn't a book reader and he speculated some things correctly. This lead to people going "omg closet book reader!" or some shit. Would the moderator have to disallow all speculation posts (which makes this thread get like 5 posts a week, consisting of "oh my God! Becky, look at his squashed head!") or only disallow correct speculation posts, thereby confirming whoever was speculating it and spoiling that for them?
We just need people to stop freaking out about spoilers and then bitching for 50 posts afterwards. Of the book readers I know of (and I've read the book) none of them post spoilers. Most discuss only what has happened on the show, with the occasional background that people wouldn't know (such as the naturef Valarian steel, the disease Stannis' daughter has, etc).
I guess you missed MonGrel's posts, then. And it wasn't so much that he would post spoilers, he was very vain about it. For what it's worth, I don't recall blankslate every spoiling anything intentionally. If something came out in one of his posts, it was probably unintentional because he always seemed very careful to me.
really though, the "Well my GF never read the books and she obviously knew this would happen, therefore it should not be a spoiler to anyone" is the type of repetitive attitude that deserves banishment.
And I'm speaking from experience: years ago, when The Dark Knight was out, I posted, about 3 weeks after the movie was released: "Well, too bad Rachel is dead!" and attracted some mod heat. ...Didnt' quite get it, and yeah, I was being a dick about it, but this was my argument: it's been out for 3 weeks. If it takes me that long to see something new, I certainly won't go into a thread about it. Spoiler tags or not (this was back in FT days, so before tags, I think). Anyway, I was vacationed for a week for that one post, because I thought a spoiler from a 3 week old movies wasn't such a big deal, in a discussion about the movie. ....because it's pretty easy to not be spoiled like this.
Anyway, point being: penalties were swifter back in the day.