The point of the question, I imagine (and am giving the interviewer the benefit of the doubt), was to see how the candidate negotiated technical compromises. Merely disagreeing without exploring the reasoning behind it and perhaps finding a different solution together might be a red flag for that environment.
The guys who were originally going to do the interview were in the room. Squirming. I asked if his background was APL (you know array based stuff) and was told that APL, and I shit you not, 'was not A Programming Language'.