Authors, who say that they “don’t not know” whether their book is satire, quite probably lie. Such honest lies are less boring that telling that they won’t tell. (That is a difference to presidents who lie openly because it shows that they have the power to do that.)
Of course “The Hunting of the Snark” contains satire. Dodgson wasn’t stupid. Satirists who explain their work would kill their work. E.g. in case of the “bathing machines“, “The Hunting of the Snark” took a reference to one of Carroll’s obvious satires.