He was an (important) employee but did not speak for, or set the NSA agenda. He's also disgruntled. This makes the quality of the source less than ideal. Now if he had some sort of memo or recording that would change the source, and could provide more credibility.

Although that's true, I consider anything he says about the NSA's current activities and goals increasingly inaccurate the longer he's not there.

I think it is fair to say that the NSA's activities and goals have not become "better" (from the perspective of civil liberties) since 2001.