Of course, Nawaki, with his cheats, was not without ways to make use of the prisoners. The simplest method was to extract their chakra and use it as energy for Zero-Tails' black-tech devices.
However, chakra-based black technology was currently Konoha's core secret. It had only been applied to a small number of weapons and had yet to be widely adopted elsewhere, so it could not be revealed yet.
Once prisoners were used as batteries, they would have to be imprisoned for life to keep the secret sealed. That was no different from slaughtering them, so Nawaki had not done so.
If Kumogakure could not offer enough benefits to ransom these prisoners back, then to Nawaki, they were little more than tasteless scraps—perhaps even a waste.
And given Kumogakure's current circumstances, with even its nest having been raided and all its supplies and wealth becoming Nawaki's spoils of war, it was already struggling to survive. How could it possibly afford anything?
It was also worth noting that the reparations in the treaty signed by the Daimyo would not be paid immediately in cash. The Land of Lightning's treasury had likewise become Konoha's spoils of war. Those reparations would be gradually repaid as debt after the war. In other words, the Land of Lightning's government would be working for Konoha for a long time to come. They could not spare any money to support Kumogakure either.
Dodai had calculated this precisely when he demanded the prisoners' release, because he knew that neither the Raikage nor the hundred thousand prisoners held much value to Nawaki at the moment.
"Lord Nawaki! You know Kumogakure's current situation. We truly cannot offer any bargaining chips! The only thing we can give is Kumogakure's friendship, and we hope Konoha will accept it. This is also the outcome