(Chiyo's true words were that he for some reason "couldn't" avoid the attack, NOT that he chose not to. We shouldn't make our own meanings up about her speculation. That must be left to the reader. (2 different arguments: "Hesitation" or Suicide."))
Reward…!! (褒美…!!, Hōbi…!!) is chapter 275 of the Naruto manga.
Although she is using a life-transferringtechnique, since Sakura was not dead, Chiyo does not die by reviving her. Sasori is disappointed that he has not been able to kill anyone and laments that he is now dying because he could not completely convert himself into a puppet. As his life wanes, he does something "pointless": as a reward to Sakura for surviving, he tells her of a spy within Orochimaru's ranks that he was scheduled to meet in ten days' time at the Tenchi Bridge. He dies in the embrace of his Mother and Father puppets and Chiyo speculates about Sasori not being able to avoid her last attack. She collapses, still poisoned, but refuses Sakura's offers to take her back to Sunagakure, claiming to still have something to do. Meanwhile, Naruto and Kakashi are still following Deidara. After preparing his Mangekyō Sharingan, Kakashi tells Naruto to start.