According to Chapter 16, why would a desire-fulfilled Sadguru like Sai Baba accept offerings or service from his disciples?

Chapter 16 explains that a Sadguru is 'Aptakama,' meaning one whose desires are already fulfilled and who is an ocean of Truth, Consciousness, and Bliss. He does not need anything from a disciple. However, the chapter clarifies that he accepts service and offerings to fulfill the disciple's own desire to serve. By allowing this service, the Sadguru helps make the devotee desireless. It is also noted that Baba accepts any offering, even a leaf or flower, given with sincere faith and love, but will turn away from anything offered with pride, thereby teaching a lesson in humility.