I understand Sai Baba became very upset with the author for reading the Bhagavat instead of coming to the Masjid to listen to his stories. Why did Baba have such a strong dislike for the practice of reading scriptures?

This interpretation is incorrect; Sai Baba did not dislike the reading of scriptures. In fact, the opposite is true. As described in Chapter 18, the author paused his reading of the Bhagavat to go hear Baba's stories. However, Baba's mind found 'no satisfaction other than the Bhagavat, which had been left in distress.' For this very reason, Baba insisted that the author return and read the remaining part of the text. This act shows the immense importance Baba placed on completing the reading of sacred books, rather than any disapproval of the practice itself.