It’s the appearance of impropriety that loses public support. Facebook not caring about stuff like this appearing to be non-private is a perfectly legitimate reason to distrust them and stop using the service. If they really valued the principle of user privacy at all they would do everything they can not to be *perceived* to violate it. The fact that they don’t should be very disconcerting to all. Regardless of whether not the common perception is accurate.
Facebook isn’t scholarship. There is no secret codex. What the public thinks is essentially what is, at least that’s how Facebook should treat it if they want us to take them seriously as a responsible, adult service.