Symbolically, the Dalton's are "blind" to the fact that they are making a fortune off of the black belt while overcharging them to live in squalor. Then, they justify this to themselves by "rescuing" a kid or two by offering them menial jobs (Daltonism=blindness if you look it up). In Wright's plot development, it is important that Bigger commits the murder in a moment of panic, or the reader would be too overly turned off to his character. The idea of "fear" (ever present in part I) is at its highest point in this bedroom scene--Bigger knows (completely believes) that he will likely be jailed for attempted rape just getting caught in this situation.
