Why did Ranbir Kapoor call Imtiaz Ali a traitor?

Ranbir Kapoor recommended Alia Bhatt for Tamasha but the film went to Deepika Padukone. However, director Imtiaz Ali cast her in Highway after meeting her at a function. Initially, Imtiaz wanted an older actress for Highway, but Ranbir convinced him to meet Alia. Highway, featuring Alia Bhatt and Randeep Hooda, earned Rs 30 crore in India.