No, I've just read in the Deathstroke topic that he made the pitch and was refused.
But I remember he saying that Dick is a boring character (not by himself, but how he is written) and needs a new development, starting with the mask: he wanted to give him a mask which shows his eyes, instead of hiding.
Also, he wanted to bring Dick (and Damian) in the Defiance story line.
I think Priest asked to work on character development, as being a leader and a mentor to young heroes, and also making some shady choices (like in Lazarus Contact), but it's hard to guess more.
I'm still hoping Priest can write at least a Titans run.