It was a lighthearted joke.I don't know if you are a traveler from a different dimension, but in this timeline KD is leagues better than Devin Booker.
The reason KD wants to play in Phoenix IS Devin Booker, and Monty. It doesn't make sense to trade him away, that would defeat the purpose.
James Jones is a win now guy , and trading book for Durrant is not win now.