WTF indeed!!!
It was actually treason...the judge used the term treason.
18 U.S. Code § 2381 - Treason - Whoever, owing allegiance to the United States, levies war against them or adheres to their enemies, giving them aid and comfort within the United States or elsewhere, is guilty of treason and shall suffer death, or shall be imprisoned not less than five years and fined under this title but not less than $10,000; and shall be incapable of holding any office under the United States.
Even the likes of Vox are saying the comment is over the top:
Michael Flynns judge suggested he might be guilty of treason. Hes not.
The judge was asking the prosecutor if Flynn might have committed treason, and the answer was no. Context matters,