I think it’s important to consider the doctor’s personal experience with James and torture. After the street assassination attempt nearly killed him we find out the good doctor had him followed to see if the British empire/EIC really wanted him dead. After crudely sewing James’ knife wound Dumbarton tries to obtain information from him by means of extreme pain. Delany plays along just to have the doctor comment that he takes pain like a stone and then discovers that he wants a tea monopoly and that he was basically playing along and enduring the torture by choice.
I believe that when Dumbarton says he will not leave until his colors are their appropriately American hues, a moment of dialogue I found poignant, that he knows that his identity is safe because no amount of pain will get James to break and talk to the crown.
David Essen Lütz