Language-capable robots hold unique persuasive power over humans, and thus can help regulate people's behavior and preserve a better moral ecosystem, by rejecting unethical commands and calling out norm violations. However, miscalibrated norm violation responses (when the harshness of a response does not match the actual norm violation severity) may not only decrease the effectiveness of human-robot communication, but may also damage the rapport between humans and robots. Therefore, when robots respond to norm violations, it is crucial that they consider both the moral value of their response (by considering how much positive moral influence their response could exert) and the social value (by considering how much face threat might be imposed by their utterance). In this paper, we present a simple (naive) mathematical model of proportionality which could explain how moral and social considerations should be balanced in multi-agent norm violation response generation. But even more importantly, we use this model to start a discussion about the hidden complexity of modeling proportionality, and use this discussion to identify key research directions that must be explored in order to develop socially and morally competent language-capable robots.