What do you gain from calling normal people interested in their privacy with the grave name of "tinfoil hat"?

A false sense of superiority and a big red flag.

Then you're using "tinfoil hat" with a much different definition than the usage I've generally seen. I tend to see the term applied in cases where somebody is mistaken about matters of fact, not merely differences in value judgments about the facts. It's the difference between "Is there meat in this dish? I'm vegan." and "Is there meat in this dish? All meat dishes are made from dolphins.". The former is reaching a different conclusion based on the same facts, whereas the latter is reaching a different conclusion based on erroneous understanding of the world. Only the latter is "tinfoil hat".

By calling a difference in value judgment "tinfoil hat", you are stating that they are wrong about the facts, not merely that they care where you don't.