Sounds to me like he was preparing to take the Celtics offer but the Jazz reached out and said something to change his mind at the last second - in other words, journalists had the right scoop but Hayward reneged right as they were announcing it, precipitating this whole mess.
I'm trying to be optimistic, but unfortunately I think he's staying in Utah. Jazz got him to change his mind, and now he's just trying to figure out how not to be the bad guy for publicly backing out on the Celts.