Li Yao agreed with the mental devil.
Neltharion's every action consumed a lot of fuel. Having entered the Divinity Transformation Stage only recently, he could not control his models of spiritual energy very well, either.
Should he make any error in the construction of attack models at the critical moment in the middle of a danger, one ultimate attack would drain all the energy of the device.
Besides, as a piece of high-precision tiny magical equipment, Neltharion was too eye-catching, with too many traces of the Star Glory Federation's style on it, which would be hard to explain once the Immortal Cultivators discovered it.
Moreover, he had come to the planet to search for intelligence, resources, and maintenance magical equipment. It was certainly not a good idea to act stealthily all the time. He was desperately in need of a body that could easily integrate into the local environment and had a huge storage space.