The Metamorphosis by Kafka is a story of revenge taken by himself on the wrongdoers, especially his father.This book must be read in the light of his letters to his father for emotional abuse.
This transmutation is an innovative way to inflict retribution upon those who couldn't come to realization.
If this book precedes his letters to his father, it indicates a state of repression. It is not a satyagraha but a form of passive resistance.
A day comes one turns vocal,bitter about the wrongs happened to himself.He musters courage to react.There is no reason to incriminate the helpless sister of a destitute brother.
I am sure that the Saturn in the horoscope of the protagonist must be in retrogression in his parental house!