"Whistleblowing" does refer to disclosing morally bankrupt behavior that isn't technically illegal, and NDAs are nefarious if they cover anything other than trade secrets.

Merriam Webster defines whistleblowing as:

> one who reveals something covert or who informs against another especially : an employee who brings wrongdoing by an employer or by other employees to the attention of a government or law enforcement agency

Wikipedia further asserts:

> Whistleblowing is the activity of a person, often an employee, revealing information about activity within a private or public organization that is deemed wrongful – whether it be illegal, immoral, illicit, unsafe, unethical, or fraudulent

Arguably, nothing the NSA was doing was illegal. Was Snowden not a whistleblower?

And if something illegal has happened, non-disclosure agreements can't be enforced regarding disclosure of that activity. At least, not in the US.