The book mentions that some of Baba's actions were a 'spontaneous play of Yoga for the sake of the devotees' salvation.' How does his physical departure fit into this?

Chapter 43 frames Sai Baba's entire existence, including his departure, as part of this divine play for his devotees' benefit. His leaving the body was not an end but a transition that ultimately served their salvation. By burning his body in the 'fire of Yoga,' he merged into his unmanifest, all-pervading form. This act allowed him to move from a localized presence in Shirdi to a universal one, becoming one with Brahman and filling the entire world. As the text explains, he now resides in the hearts of all devotees, making his guidance and grace accessible to everyone, everywhere, based on their own faith. This transition from a physical form to an omnipresent spiritual force can be seen as the ultimate act in this 'spontaneous play of Yoga.'