As you admit, the question asker might very well have been genuinely curious. The answer to their question doesn't seem blindingly obvious to me (although I can certainly speculate about good reasons that grading isn't automated). I can't tell what you mean by "unacceptable" (perhaps there is some cultural taboo you're referring to here?). And it also doesn't seem "dangerously naive", which might apply where someone asking this question had decision making power in a critical situation, but clearly doesn't apply here.
By the very criteria you lay out, this doesn't seem like an instance in which ridicule was necessary or good. To me, it feels like a weak justification for bullying someone who thinks differently about something you obviously feel very strongly about.