Is this specifically unauthorized, though? The user is permitted to use Apple's services, and Apple has, as far as I know, not announced that third party apps may not use their services.
If Apple files a complaint with Google it will definitely get taken down under this clause, so I think the only way it will stay up is if Apple doesn’t care.
With the trouble Apple goes through to ensure you are accessing APNS from an Apple device including obfuscating the signing algorithm and requiring unique hardware identifiers I think it’s safe to assume they don’t want 3rd parties accessing their services.
what does this mean? plenty of 3rd party signal clients exist (flare being a well-known one); signal explicitly factored out a libsignal presumably to _encourage_ this.
i’ve run multiple 3rd-party signal clients, even alongside the official apps, and never seen any problems or warnings.
It would be nice if third party clients were allowed to connect, but it's totally understandable if they don't want to allow it. Servers cost money, and misbehaving client apps that you have no control over sound like a pain in the ass.
