Mordekaiser's Mace of Spades doesn't work with Devour enchament

So i was playing one for all and we got Mordekaiser. I thought devour would work well with the q, but quickly learned that the q wasn't considered a basic attack at all. Is this intended or just a bug( Once sated the q takes all three attacks instead of two) . I understand that the wording doesn't imply that it is a basic attack but since spell-blade passive works with the morde's q which says specifically that on the next basic attack; it seems like a little contradiction.