That's not entirely fair. The argument isn't "users are using the service to break the law" but rather "the service is facilitating law breaking". To fix your signal analogy suppose you could use the chat interface to request copyrighted material from the operator.
That doesn't change the outcome being the same in that the app has to send the plain text messages of everyone, including the chat history of every user.
Right. But requiring logs due to suspicion that the service itself is actively violating the law is entirely different from doing so on the basis that end users might be up to no good entirely independently.
Also OpenAI was never E2EE to begin with. They were already retaining logs for some period of time.
My personal view is that the court order is overly broad and disregards potential impacts on end users but it's nonetheless important to be accurate about what is and isn't happening here.
Again keep in mind that we are talking about a case limited analysis of that data within the privacy of the court system.
For example, if the trial happens to find data that some chats include crimes committed by users in their private chats, the court can't just send police to your door based on that information since the information is only being used in the context of an intellectual property lawsuit.
Remember that privacy rights are legitimate rights but they change a lot when you're in the context of an investigation/court proceeding. E.g., the right of police to enter and search your home changes a lot when they get a court issued warrant.
The whole point of E2EE services from the perspective of privacy-concious customers is that a court can get a warrant for data from those companies but they'll only be able to produce encrypted blobs with no access to decryption keys. OpenAI was always a not-E2EE service, so customers have to expect that a court order could surface their data to someone else's eyes at some point.
