Fair that it was abrupt of me to put it that way.

But to make clear what I was saying, I really should have responded to the parent, who says: "It's extremely hard to believe that even a malicious scientist could convince himself that a horse cannot be ridden into town."

My point being that a malicious test-giver could certainly deny that as a valid answer. I don't know that I believe that anecdote happened, but it is assuming good faith to think that it couldn't happen because no one would ever reject "horse" as an answer.