Interviewers may sometimes ask questions that seem odd and strange, or morally questionable. These questions may not have a right or wrong answer.
They are intended to assess your ability to think independently, articulate your ideas and stand by your judgement in a debate.
They could also be intended to assess your ability to reason logically and handle difficult or awkward situations that are essential for certain professions.
The key is to be able to gauge the nature of the questions, and answer them confidently and with maturity.