I don't think Harding's that bright, but I'm also not sure he even gets the moral exoneration of being an idiot. Useful to state intelligence? Definitely. Unconsciously so? Hard to say. The Manafort/Ecuadorian embassy story was cut from whole cloth. One of the co-authors, later deleted from the online version, was one Fernando Villavicencio, an incredibly sketchy character with ties to US intelligence. For Harding, being a useful idiot, while theoretically possible, is a best-case scenario.