Jazz can't trade Hayward unless it's a sign and trade during the offseason, which is AFTER the draft. The Jazz can't talk to Hayward about this possible move, so they have zero inclination that Hayward would accept this trade, so the Jazz would have to take the player Orlando wants with the hope that a) Hayward agrees to the trade, b) Boston and Hayward agree to terms, c) Orlando would back out after drafting their own player and meeting with him for two weeks, d) Boston makes the gamble that the Jazz wouldn't match an offer without the sign and trade, and e) NBA wouldn't see a deal as fishy and investigate it.
You CAN'T negotiate backwards. You're just leading yourself to disaster.