The book says Baba merged into the 'unmanifest' and became 'one with Brahman'. How does this allow him to still interact with and protect his devotees?

According to Chapter 43, Baba merging into the unmanifest did not diminish his power but rather expanded it beyond physical limitations. The text clarifies that Baba was never confined to his physical body, and to think so is improper. By transcending his material state, he now "fills the moving and non-moving world" in his true form. His presence is not gone; it has become all-pervading. He remains in the hearts of his devotees, and as the chapter states, "Whatever the feeling in one's mind, such is the experience even today." This suggests his interaction is now on a more profound, spiritual level, where he continues to protect his devotees and keep them spiritually "awake" from his unmanifest state.