Sarutobi Toru also strongly suspected that Otsutsuki Kaguya's true purpose in using the Infinite Tsukuyomi to turn humans into White Zetsu was to extract the Chakra from them, not to create some White Zetsu army.
After all, with White Zetsu's level of combat power, asking them to take part in battles involving the Otsutsuki celestial beings would be asking far too much of them. Even the White Zetsu modified by Sarutobi Toru would be useless in a fight against the Otsutsuki Clan, not even qualified to serve as cannon fodder.
As for the fact that humans at the time did not yet possess Chakra, wouldn't they gain it after being transformed by the Infinite Tsukuyomi? Chakra was a mixture of physical energy and spiritual energy; it was not some fixed quantity.
Not having Chakra did not mean they lacked physical or spiritual energy. All they needed was a catalyst that allowed them to create Chakra. Then every person could become a Chakra generator.
Hadn't Otsutsuki Kaguya stated it quite plainly when she appeared? She wanted to gather all the Chakra in the world. She never said she wanted to turn everyone in the world into a White Zetsu army.
That showed that, in her eyes, gathering Chakra was the true objective. White Zetsu were merely a way of putting waste to use.
After absorbing a massive amount of Chakra, the God Tree might produce another Chakra Fruit. Even if it did not produce one, as the Ten-Tails Jinchuriki, Otsutsuki Kaguya could still grow stronger after the God Tree absorbed Chakra. That was her true purpose.
After hearing Sarutobi Toru's actual thoughts, Tsunade's voice trembled slightly. "Toru... y-you wouldn't be planning to launch the Infinite Tsukuyomi, would you?"
Sarutobi Toru was not that cruel. He actually intended to use the Hormone