Why did Sai Baba become angry when the narrator stopped reading the Bhagavat to come listen to him instead?

The source material from Chapter 18 does not state that Sai Baba became angry. Instead, it offers a more subtle description of his sentiment. When the narrator put the book aside mid-story to go to the Masjid, the text says that "in Baba’s mind, there was no satisfaction other than the Bhagavat, which had been left in distress." Rather than anger, this indicates Baba's deep reverence for the scripture and the importance he placed on completing the reading. For this reason, he insisted that the narrator go back and read the remaining part. The narrator remembers this incident not as a rebuke, but as a "great marvel of Baba’s" where "love overflows when remembering it."