a) He or his agent could easily have said to Ainge on July 4, "I'd like to sign with you but a requirement is you work out a way for Utah to get a trade exception." Would have cost him nothing, and Ainge would have obviously agreed.How? You expect Hayward to refuse to sign with the Celtics just because Ainge won't help the Jazz? What's he going to do then? Go sign with Indiana? It doesnt bear repeating because it's a ridiculous assertion.
b) Even now, he could probably go to Ainge and say, "Make this happen before I sign with you. I owe it to the team and fans in Utah," and I doubt Ainge would resist too hard. Especially if Utah is willing to throw in a 2nd rounder which they undoubtedly are.