what do you see as his primary motivation for quitting his job? What other factors motivate him?

Sammy seems to want to take a social stand. Sammy understands that the world is not a fair place. He now sees the social, cultural, and sexual injustices that will never go away. Sammy knows that if the supermarket incident is strong enough to make him quit a job he needs, he will have a tough time living in this world. Still, he thinks the injustice is enough to quit his job and try something else.