Does Sai Baba's benevolent nature towards his devotees continue even after he left his physical form?

Yes, absolutely. The text explicitly confirms that Sai Baba's role as a benefactor to his devotees is eternal and did not cease after he left his body. Chapter 48 states that by merging with the Unmanifest, his form attained formlessness, but his quality of helping his devotees does not end. It assures followers that "Whatever actions were performed while in the body, the same are experienced today in the Unmanifest state by those who are devoted to You." This demonstrates that his vow to be "subservient to his devotees" is an unending promise that transcends his physical presence, offering continuous support and grace to those who seek refuge in him.