Because the decision rested with Konoha, not Sunagakure.
Orochimaru held a certain degree of authority in the negotiations. If they wanted to save those shinobi, they had to follow Konoha's terms. Even if Orochimaru made outrageous demands, Sunagakure would agree in order to save them.
Orochimaru was now even more curious about Uchiha Yū's deadly poison. What kind of poison could leave Chiyo helpless?
"Once they arrive, they will remain under supervision at all times. Only genin may come, and they will not be allowed to damage the camp."
Only after making thorough preparations did Orochimaru dare let them in.
Still, Orochimaru was rather surprised by how greatly they had yielded. It seemed that the poisoned person's identity and status were enough to make Sunagakure back down.
"It looks like they were exposed for a long time, which is why they became contaminated by the radiation."
Yū understood his nuclear radiation ability well. In order to wipe out the enemy shinobi force, he had pushed the radiation to its limit.
Combined with the altered terrain, there should have been no living survivors able to escape. The corpses had likely been recovered during Sunagakure's later investigation, but these uranium elements caused indirect radiation damage.
The lethal effects would be reduced, and those harmed by the radioactive elements would show milder symptoms. Yet prolonged exposure to radiation would cause mutations in the body's cells.
"I can more or less guess who it is."
A faint smile appeared at Uchiha Yū's lips as he voiced his speculation:
"Orochimaru-sensei, the best poison antidote expert in Sunagakure is undoubtedly Chiyo. She was in contact with my ability for a long time, which caused the indirect spread."
"Only Chiyo could make them concede this much."
Unless there was special lead-based protection, or some particular medicine capable