The phrase "stood in lieu of" means to substitute for or act as a replacement for someone or something. Antonyms for this phrase could include "absent," "missing," "unavailable," "vacant," "neglected," or "ignored." These words imply a lack of presence or attention, the opposite of acting as a stand-in. Other antonyms could be "unrelated," "unconnected," or "unassociated," suggesting that there is no replacement or substitute available. Alternatively, "permanent," "unchangeable," or "indispensable" would indicate that the person or thing cannot be substituted or replaced, further emphasizing the contrast with "stood in lieu of.