Would a reasonable and informed observer question the judge's impartiality who allowed an AUSA, through his own acknowledgement, to prosecute in the proceedings he's a witness of?

If a judge demonstrates favoritism under § 144, for the AUSA who became a witness, is that judge impartial?

Whether a reasonable and informed observer would question the judge's impartiality when the judge allowed an AUSA who became a witness in the proceedings to prosecute the case