This is nonsense. Self-censorship occurs whenever somebody censors himself. In polite conversation we might call it discretion (or valor). In a fiduciary or confidential relationship, we might call it adherence to the duty of confidentiality. In a contractual relationship, we would call it nondisclosure. In employment, on one hand we might call it professionalism—or self censorship on the other—depending on the context.
Regardless, the term "self-censorship" is not germane to or inherent in only citizen-government interactions.
People self-censor constantly on social media. You're not worried about the government taking a tweet out of context and driving your reputation into the ground, the mob of internet idiots has that covered. Fear of internet mobs causes people to censor themselves, and a definition of "censorship" that doesn't cover uses like that is not a particularly useful one.
Regardless, the term "self-censorship" is not germane to or inherent in only citizen-government interactions.