Maybe the most moral thing to do would be, should you find yourself employed at an immoral company -- Fight to do everything in your power to change the company

Maybe the most moral thing to do would be, should you find yourself employed at an immoral company -- Fight to do everything in your power to change the company's course, while drawing your salary (and thus their resources), and not contributing towards the immoral actions at all? Basically you'd be forcing them to fire you at some point, but until then, you're fighting against it for as long as possible and thus hopefully maximizing the chance of changing course.