I don’t disagree with a lot of what you wrote, but the Kings hold all the cards here, and they can’t really get upset if the Kings choose to not let a former lottery pick, who as you said does provide some value, just walk for nothing.
If I were the Kings I’d submit the qualifying offer to make him an RFA, but then inform the agent that we’d operate in good faith to do a sign and trade if the agent can work one out with a team, but that we’re not letting him walk for no compensation.