Antonyms for "are duty to" would be phrases like "have no obligation to," "are not responsible for," or "are not duty-bound to." Essentially, these antonyms suggest that there is no requirement or responsibility for someone to take action, fulfill a duty, or perform a task. While the phrase "are duty to" connotes a sense of responsibility and obligation, its antonyms distance individuals from any such responsibility or obligation. These antonyms imply that the activity or task in question is not related to the individual, eliminating any responsibility or obligation that may have been present otherwise.