According to your logic, If I create a website that maps Hacker News usernames to metadata, and because I know you in real life, I enter your information (name, occupation) on your behalf, and now the connection between your username and that other information is public, your privacy has not been violated, because this is not information about you, it is simply a series of letters connected to another series of letters.

I think what you mean to say is that it is not the app that committed the betrayal, it was the source who was enabled by an app that otherwise had a non-nefarious purpose. Which, fair point, but I don't think the article would disagree.