The word "most custodial" implies a sense of responsibility or caretaking, so antonyms would include words that convey the opposite meaning. Some potential antonyms might include neglectful, irresponsible, uncaring, neglecting, or thoughtless. These terms would suggest a lack of attention or concern for the well-being of whatever is being cared for, whether it is a person, a building, or a set of responsibilities. Alternatively, antonyms could include words that suggest a lack of involvement or engagement in the caretaking process, such as hands-off or distant. Regardless of the specific antonym, it is clear that "most custodial" implies a level of attentiveness that its opposite would lack.