I'd offer it's not entirely clear that Kuminga
would make this team better. He'd certainly make the team younger, which is a necessary step for the Kings to take, and whatever talent he might have is worth taking a swing on, but mostly as a buy-low opportunity. It's less about holding the Warriors' feet to the fire and more about being opportunistic, given the very real risk that Kuminga will never become more than wasted potential.
The fact is, Kuminga remains a distressed asset because of 1) the Warriors' bungling of this whole situation, and 2) his inability to break into their rotation consistently, regardless of the circumstances that have led to his regular benching. With his value at rock-bottom, you don't bid against yourself if you're the only interested party and there are no other takers. You pressure Dunleavy into accepting a deal that's low-risk for the Kings or you wish him the best of luck. Take it or leave it, indeed. If the Warriors pass and would rather Kuminga's extension rot on their bench for the next two years, then so be it.
Kuminga could be an interesting get, but I haven't seen enough to convince myself that he's worth parting with a piece I otherwise wouldn't want to give up.