There are several synonyms that can be used instead of "doeth an about-face". One such synonym is a "reversal" which means to change direction or opinion. Another synonym is "turnaround" which refers to a sudden transformation or change of attitude. "Halt" can also be used to describe the act of stopping or ceasing something abruptly. "Flip-flop" is a colloquial term that means to change one's mind frequently about a decision or opinion. Finally, "backtrack" can be used to describe the act of retracting or reversing a previous statement or decision. All of these synonyms emphasize the idea of a sudden and complete change in direction or opinion.