He was one who opened the Bloodline Wheel, his atman's and mortal body's longevity were the same. If his mortal body died, his atman would disperse as well.
Only by ascending his soul into the Void World could he save his soul from death. In addition to the worships, one could theoretically continue to live eternally in the Void World.
However, in order to see Zhong Yue, the Nong Sovereign chose not to ascend his soul. Instead, he stayed back just for Zhong Yue, to tell the latter of the humans' affairs, things that Zhong Yue wouldn't know of. The uncompleted works of humanity's rise, and every other plan, dreams, and ideal Nong Sovereign himself couldn't have done it himself.
Zhong Yue stared dumbly at the elder's soul who was smiling ear to ear on his arrival. Was there ever a need to take the risk of dispersing his soul just to meet with Zhong Yue? Was it actually worth it?