Was it really a children's book or did he write a book for adults, but it was just so damn stupid everyone assumed it was a children's book, and never bothered to clarify with him?
If it's the type of thing I think it is then it's a blatant propaganda book aimed at children but ends up being consumed almost exclusively by adults, because the kids want nothing to do with it and would rather just play Fortnight.
I mean, the GOP has long aimed their rhetoric at a fifth-grade reading comprehension level, so in a real sense everything they put out is a children's book. Trump's "innovation" was targeting a third-grade reading level.