I think if you're going to ask a subsequent question about an algorithm for predicting when bread is done proving, you are allowed to ask about leavening agents. That way, you can bypass the long explanation, and just say "Given n loaves of bread with X characteristics, design an algorithm to predict when they are done proving." That might actually be a decent data science interview question.

I used to ask an algorithms interview question based on bridge (the card game), and I asked a setup question of "have you ever played a trick-taking game?" That lets me see if I need to use the short explanation or the long explanation, and if you answered that you knew how to play bridge or spades in a follow-up question, I would ask a much harder version. If you've never played a card game in your life, I would switch questions (this has happened several times). In real life, most people understand that this kind of question is a setup for a subsequent algorithms problem, not a quiz of your knowledge of bridge or prime numbers (particularly after you say that you don't know number theory).

The interviewer didn't care how much you know about prime numbers any more than I cared about whether you knew how to play hearts/bridge. The interviewer was almost certainly trying to figure out how much he needed to explain in the problem statement for the algorithms problem.

Responding with snark only shows that you are not willing to work with them in good faith, and you are not willing to see where the question is going. It shows that you think you know what they should be asking you, and you have contempt for them because they are not running the interview the way you prefer.

By the way, if the primes thing was actually a quiz question that didn't go anywhere, I would encourage any Django programmer to say a gentle "fuck you" at the end of the interview. I certainly would.