If holism is even coherent as a metaethical position, then the claim that discerning relevance in one case 'immediately shows' universal relevance begs the question against particularism.

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Discerning relevance(identifying what's important in a particular moral situation): Figuring out which facts or details actually matter for making a decision or judgment.
Holism(Mid-twentieth-century individualism/holism debates): A position in the individualism/holism debates that treats social entities as irreducible to individualistic entities, without denying the existence of the non-social
Metaethics(as the general field this statement appears in): The branch of philosophy that asks questions about morality itself—like whether moral truths actually exist, or what makes something right or wrong.
Particularism(See section 4.3 of source): The principle that the properties of a composite system are wholly determined by the intrinsic properties of its parts; implies Outcome Independence according to Teller (1989)

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