Your analogy should be narrowed according to the facts of this case. Assuming that the author's guesses about the app's behavior are correct, this is a case of software checking for one specific tool — a tool that's strongly associated with piracy. A defendant in the physical world wouldn't necessarily have a reasonable expectation of privacy if there were indications that he or she was engaging in unlawful conduct. So it's unfair to say the app's behavior would be obviously illegal or that it's comparable to a secret inventory of all of someone's physical items. That said, I'm not justifying the hijacking of the author's Twitter. That's not an appropriate remedy by any standard.