Is Sai Baba's presence now confined to Shirdi since he left his body there?

No, his presence is not confined to Shirdi. While he left his physical body within Shirdi, Chapter 43 makes it clear that we should not allow such a doubt to enter our minds. It states that it is improper to think Baba fit only within his three-and-a-half-cubit body. After leaving his physical form, he became one with Brahman and, in his true form, now fills the entire 'moving and non-moving world.' The text compares him to other great saints like Gyaneshwar and Tukaram, whose influence was not limited by place or time, asserting that Sai's divine presence is likewise universal and unbroken.