Section 22 pages 270-end Q 3

Even though the father is there, the boy still looks alone. It is as if the father is on loan and eventually the boy will be by himself standing with his tattered suitcase waiting for something   The man looks at his son, "like an orphan waiting for a bus" that will never come. 

Because soon the boy will parentless, like that of an orphan, and the man is scared that the boy will wait for someone to come save him, hence the reference to the bus.