It is a shame that you are being asked to retroactively excuse someone from the law. Ignorance of the law was no excuse for the telecoms. Bowing to executive pressure by teh telecoms then or congress now is unacceptable.
The last public acknowledged time the executive demanded this kind of cooperation the telecoms refused. They cited the law. They should have done so this time and they should not be shielded for having forgotten the law.
As a soldier, I was told following an unlawful order did not absolve me of my responsibility. Do not absolve telecoms of their responsibility for their choices.