You do know that everyone who signs up as an Age Insider has signed an NDA?An NDA is entirely about enforcement, as its entire point is a legally binding and enforceable document. Otherwise you could say the same without having your corporate lawyer reviewing it, ensuring the persons receiving it were briefed of its coverage, and paying retainer for someone to administrate and act upon them in the event of breach.
To achieve the same outcome you describe you could just say "hey don't tell anyone," without the thousands in overhead and ODC of bothering with an NDA in the first place.