Muzan does not want to eat Nezuko in the traditional sense. He desires to absorb her.
Muzan's motivation stems from Nezuko's unique ability to resist sunlight, a weakness that has plagued him for centuries. He believes that by absorbing her, he can gain her immunity and achieve his ultimate goal of becoming invincible.
While Muzan may initially have considered consuming Nezuko for her blood demon art, his interest shifted toward absorption after witnessing her resistance to the sun. This makes Nezuko a valuable asset in his quest for power and immortality.
