See, my first thought on reading the question is that this guy was fishing for answers to the sorts of questions he's not legally allowed to ask—relationship status, family plans, and so on. This is reinforced (at least to me, unless I'm misreading) by the comment that "If I know what matters to them, I can right away tell if the same things matter to me (the hiring manager) and the organization at large."
So, aside from being manipulative, which lots of interview questions are, this one also struck me as unethical and borderline illegal.
A pity your comment is so low on the list. This isn't even borderline illegal - at least here in South Africa, if you ask a question like this of me and I don't get the job, and I think it's because I mentioned my 10 kids in answering this question, I have pretty solid grounds to charge this as a unfair discriminatory question and seek recourse from the CCMA (the legal entity that deals with these sorts of issues in SA).
So, aside from being manipulative, which lots of interview questions are, this one also struck me as unethical and borderline illegal.