Kaz won't be entirely helpful as a negotiator, because his business is war. But he'll have an absolute last choice recommendation. And emphasize that it should be used as a last option.

And it's to remind them that the entirety of Cadacus Primary was destroyed by this ship. While it also helped with evacuation efforts, a crew of significantly smaller number and less dangerous individuals destroyed the entire planet. And that it won't be worth it to them to engage in mutually assured destruction, because if they try that is what will happen.

Rather than war, they should focus all their financial efforts on resettling and rebuilding. This is a fruitless venture and will bring no actual benefit to their people.