We should certainly not be perpetuating further harm to others or to the environment. Suppose that workers at ExxonMobil are trying to unionize. We have two choices: to help them improve their lives, or to keep away so that their lives will be worse. Neither choice has any effect on use of fossil fuels. So radical organizers can both help them unionize and improve their lives, and convince them to find a different way to survive and work for ending the use of fossil fuels.
