Moral relativism concerns the dependence of moral truth or justification on a framework, culture, or standpoint. Descriptive disagreement is a separate claim about what people believe. An argument for relativism must explain why disagreement supports framework dependence rather than error, incomplete information, or different circumstances.
Several claims must be distinguished: people disagree, justification depends on a framework, and moral truth itself is relative to a framework. The first does not logically establish the others. Disagreement could arise through missing information, different circumstances, or mistaken reasoning. Conversely, an objectivist cannot settle the issue by announcing that their own standards are universal. The debate requires an explanation of how moral claims are justified and what authority a framework can legitimately possess.