After learning the truth, how did Dev rationalize his failure to recognize Sai Baba in disguise?

Upon reading Jog's letter and learning the truth, Dev felt immense shame and regret. According to Chapter 40, he rationalized his 'delusion' by recalling the sequence of events. He remembered that the Sanyasi had first appeared for fundraising purposes before the Udyapan invitation was even extended to Sai Baba. Because this initial meeting was for collecting funds for cow protection, Dev did not associate the Sanyasi's later return for a meal with Baba's promise. He admitted that he forgot to pay attention to Baba's specific words: 'When I come for the meal, two others will come with me.' This prior context caused the delusion that prevented him from recognizing his Guru.