Your reason #3 is applicable in this case: that the law prohibits any further release.
That is so glaringly true that even the diehard Leftist press could not refute it.
That would be true if this were a legal proceeding and one party refuses to comply with a subpoena that is issued under the authority of a court. But in this case there is no "court" because this involves two branches of government who are relying on powers vested in them under the U.S. Constitution.