[zephyrfalcon]

It does not mention how the question was put, and in which context. If it was clear from the start that the OP was expected to use OO, then it would not be smart to start with the bitboard implementation and then continue to argue about it. ... But if the question simply was, "how would you design a chess game", with no other context, then it would be reasonable to assume that the interviewer would want to hear your best solution... and for that he chose the non-OO bitboard version, based on his previous experience with chess engines.