This story actually vindicates the DOJ in its ongoing stonewalling of Congress.
No, it does not.
The Congress is the separate branch of the government with Constitutional oversight. Period!
The DOJ is part of the Executive Branch, not an independent branch. It has no prerogative to act like a loose cannon.
There can be no valid justification for the stonewalling. If you do not want Congress to have such oversight for any reason, then campaign to have the Constitution amended.