This season he wasn't going to play much anyway. Just because offensively he is polished, there is zero way he can guard an nba center or even power forward in the post. He would be a liability on defense. Jabari has much more of an nba body to be able to defend the post. My guess is chet was only gonna see around 10 or so minutes a game anyway, when the other teams go small ball.
That was a big issue before he entered the NBA. He might want to work that out while resting, more carbo.

I agree that Jabari is more fit to be a rising star than him. Speed, strength, they need that now more than anything. Sure, a shooter had become a phenomenon because of Steph and others but in the defensive end, they won't matter much. (Steph though made a lot of progress in his defense)
Maybe he could borrow some fats from Zion.

One is trying to trim (added weight loss clause contract) and the other is being criticized for being too thin.