Forerunner Prometheans

I was just watching the IGN live stream and noticed something Josh Holmes said. From the Halo: Cryptum novel, I was given the impression that the Prometheans are a caste of the Forerunner society, but Josh Holmes made it sound like the new enemies (Promethean Crawler, Promethean Watcher, Promethean Knight) are THE Prometheans, even though they are clearly artificial constructs.

Is 343 retconning the Promethean from Forerunner caste to a class of Forerunner combat drones? Or is it a simple case of wrong choice of words?