Imagine that the NSA was only doing legitimate, useful, necessary, highly secret things (humor me here).
Can they brief Congress on what they're doing? All 535 publicity-seeking chatterboxes? No way. That's the same as issuing a press release.
So not telling Congress everything is (in principle) necessary. But who are these representatives Schneier briefed? Are they on the Intelligence Committee? If so, and they still can't get straight answers out of the NSA, that's a big deal. (And maybe the rest of Congress is saying that they don't think that the Intelligence Committee has done an adequate job of oversight.)
Can they brief Congress on what they're doing? All 535 publicity-seeking chatterboxes? No way. That's the same as issuing a press release.
So not telling Congress everything is (in principle) necessary. But who are these representatives Schneier briefed? Are they on the Intelligence Committee? If so, and they still can't get straight answers out of the NSA, that's a big deal. (And maybe the rest of Congress is saying that they don't think that the Intelligence Committee has done an adequate job of oversight.)