According to the source, why are saints like Sai Baba considered beyond the cycle of birth and death?

Chapter 43 explains that saints like Sai Baba are beyond the concepts of birth and death because they are free from the six-fold emotions and always remain in an unmanifest state. Their worldly life may end, but their spiritual attainment remains. As stated in Chapter 43, the feeling of duality completely vanishes for them as they become filled with their true form. For such beings, birth and death are considered false imaginations. They take on a physical body, or manifest, with the sole desire for the welfare and salvation of their devotees, so the conventional rules of physical existence do not apply to their eternal nature.