I think this is a common experience for anyone who interacts with the rest of the world. And, since there always seems to be Texas sharpshooter response as to why anything you describe is somehow perfectly reasonable, perhaps the best aproach is to ask, "what wouldn't you want the government to collect, or how wouldn't you like it to be used?"

If there's nothing, then you can dismiss them as not a serious person. If they have an answer you have a beginning point for a conversation that may not be a waste of time for both of you.