Actually Peter, cordierite is, indeed, mentioned in the literature, but if you look at the care & handling PDF for the stones, you'll see that, word for word, it matches the care & handling of fibrament. It also, from the picture, has the very recognizable grayish white dull cast appearance of fibrament, rather than the yellowish kiln fired cordierite.
I'm guessing that at one point this oven might have been sold with cordierite stones. After switching to fibrament, they probably failed to remove all the cordierite references in the literature. That's one theory.