Also, the trap question could easily have the opposite "right response" as it does in the post and still be defensible as something important to learn about a c

Also, the trap question could easily have the opposite "right response" as it does in the post and still be defensible as something important to learn about a candidate. Another interviewer performing the same test sequence might want to see if the candidate can change subjects quickly, roll with new circumstances, and not get flustered or stuck on a single, obsolete outcome.