Other teachers in my department see Situation Ethics and Utilitarianism as a form of relativism. This seems to me to be a confusion between there being different courses of right action for different circumstances (situation ethics and utilitarianism) and there being different right actions for one circumstance (relativism). Even if you're a utilitarian, there is still an absolute as to what one should do in that particular situation (it's just that it isn't always clear given the difficulty in predicting outcomes), and so it is not a relativist ethic. Who's right?
You're right, and the point is well-put, too!