This is the part that interests me the most. In a way, its a thousand times worse now. In a practical sense, if the story was told today the story would suggest that any agent would get this information just by asking ISP, banks and maybe Amazon for your history with them. We don't just know that you drink tea. We can predict your daughter is pregnant and know wife is cheating on you. Full blown surveillance requires little to no effort. The amount of mind games you can play with that treasure trove is why you hear concerns IC about people 'going dark'.

I suppose to me how the information is obtained is secondary. The fact that it is obtained at all is an issue. We are only recently becoming better at analytics and seeing patterns that would be considered a little creepy only few decades ago. It is normalized now.

To your point that in the story, the trivia is truly irrelevant. By itself it means nothing. State knows I drink tea. Big whoop. Tons of people these days voluntarily show off eating pastas of all kinds. It is just serves as a way overwhelm the target with a feeling of helplessness ("They know everything"), abandonment("Someone close gave them information"),hopelessness("What is the point?").

So the trivia is not threatening by itself. It is the implication that the agent knows you very well indeed and that knowledge includes trivia.

Now imagine a person visiting you with a short listing of your detailed interests, search history, suspected health issues and inferred psychological profile.

It is a lot less subtle, but it conveys same message ( I know you better than your family, doctor, bookie.. ).

Sorry for the long response, but I just wanted to make sure it is clear that trivia is just a small part of it. As Dennis Reynolds would have said: It is the implication.