Antonyms for "stand in lieu of" could include words like: ignore, neglect, abandon, refrain, surrender, relinquish, yield, or forsake. To stand in lieu of something means to substitute or replace it, so antonyms would refer to the opposite action of disregarding or giving up on a responsibility, commitment, or duty. In some cases, antonyms might also include phrases that emphasize the importance of a task or the consequences of not fulfilling it, such as "take action," "fulfill obligation," or "meet expectation." Ultimately, the antonyms for "stand in lieu of" would depend on the context and the level of urgency or accountability involved.