You seems to not understand what really happened. Cp3 wanted to leave (he lost his fate in Clippers) and he could leave for nothing this summer, like Durant did, year ago. Instead of this he proposed the trade to give at least something to his former team.
Super dumb post. CP3 was getting to leave as a FA. Irving is still under contract. CP3 OPTED BACK IN to give the Clippers a chance to get SOMETHING in return as well as give US an easier time to get him.