Think about this situation in the course of your life.
You are at some job or situation. Something else is tempting. You are excited and willing to listen, knowing that "well, if it doesnt go trough i can just stay". Suddenly the place you are at allready seeks to hire your replacement so you gotto decide fast. You become freightened, because you realise that if you wait too long, one of your choises will stop excisting and you are forced to go.
Everyone picks the decision to stay unless they are really convinced and eager to change, or have made up their mind allready.
What Marotta wants is Morata to formally tell real madrid he wants to remain at juventus, will refuse to move anywere else (kinda did that allready), and doesnt want to sit on real's bench. Teasing a high potential similar profile player (it can almost not be more similar), is exactly how you do this.