I think that while some parts of natural human morality may rest on illusion, hedonically grounded practical reasons, and at least those parts of morality that rest on them, very likely have some objective normative standing.

Leonard Katz, ‘Hedonic Reasons as Ultimately Justifying and the Relevance of Neuroscience’, in Walter Sinnott-Armstrong (ed.), Moral Psychology, Vol. 3: The Neuroscience of Morality: Emotion, Brain Disorders, and Development, Cambridge, Massachusetts, 2008, p. 409