This is just propaganda by Facebook showing everyone that it cares about your privacy. Unfortunately, I believe government all around the world are going to have a talk with Facebook about what is acceptable levels of privacy.
>>pearls+(OP)
The focus seems to be on "state-sponsored actors", not the states themselves. My guess is this is targeted at completely illegal and disavowed actors, not those that have the luxury of being able to issue a NSL.
>>pearls+(OP)
I don't think you have to comply with NSL before you get it. If Facebook is able to detect pre-NSL surveillance (I doubt government just sends batch NSLs as a prelude to investigating potential targets), they can alert you before an official gag order tells them to shut up.