I still don't see the reason why you have to trade both immediately if you trade one. I have zero delusions about Don being a Jazz player after his contract. It's not a possibility I factor into any of my calculations....and I still don't see why it's better for Don to be traded immediately versus one year later, for example. Let's say the Jazz trade Rudy for some kind of ATL package and John Collins (or insert any player we'd receive for Rudy) becomes a real star player. Unlikely, but not unfeasible. If you had already traded Don, you'd feel really stupid just like if you traded Gobert just because Hayward left. If the likely scenario happens and we're just mediocre, you can very easily trade Don at that point. I don't think he loses any value.
Having one star player is a stronger position than having zero because you can always trade that star player for the future assets.