Strange! I would have thought the Judge had been given an order to drop all charges by the “Department of Justice”, his boss!
How is the "Department of Justice" a judge's boss?
No, the judge doesn’t work for the Executive Branch under the Department of Justice.
Federal Judges, except for Article 2 Administrative Law Judges who interpret regulations promulgated by executive agencies, are employed by the Judicial Branch of our government. Their "boss" is essentially themselves, then their Circuit, but ultimately the US Supreme Court, who cannot fire them, but only Congress can fire them by removing them through House impeachment and conviction in a trial in the Senate.