Its illegal in the usa to prevent someone from talking about their salary. Most companies don't have policies that expose them to legal issues.

I also think that its debatable if indicating your salary or admiting to the fact you work somewhere, counts as talking to the press or mentioning the company, the way most people interpret that phrase. I mean, i'll admit that its highly debatable, but for example putting your resume on linkedin usually does not count as mentioning the company on social media.