In a space without value, why would one choose dialectic or synthesis as an approach? The choice of a procedure is attributing value to the perspective it fosters, which denies any true sense of nihilism. Adorno is simply being abstruse. Valuing deconstruction is holding a value.
What we tend to call nihilism itself tends to be the attribution of value to freedom from constraint. Nietzsche is one of the first people folks tend to label nihilist. But he has a definite value system, to which he is so attached that he mocks the degree to which he ends up writing like a religious figure. Wittgenstein is another person whose thought gets labeled nihilistic, but language-games are repositories of meaning, and they represent an ingenious solution humans have made to being individualistic and social at the same time. Empiricism, Cynicism, Academicism and the other cousins of Stoicism are equally not nihilistic. Each has an attachment to a given value at its root, usually a variety of freedom, authenticity, or independence. As Sartre points out in his own defense, Existentialism is the ultimate Humanism.
So yes, there is a point to denying obsessionality, seeking authenticity, honoring detachment, and there are synthetic approaches which incorporate those aims. But no, there is not a point to any synthetic approach to nihilism, because approaching nihilism implies a vector of approach, which is, in itself, not free of presumed value.
This notion of a nihilism that still supports decisions about what is and is not reasonable procedure makes me think of an old New Yorker cartoon -- "We at St Aubrey adopt a totally neutral position on religion. If you say you are not Anglican, we whip you until you change your mind. But it is not a value judgement, it is simply a methodology."