A challenge to Bix's interpretation of Kelsen and Hart's views on the normativity of law

Brian Bix discusses questions of legal normativity, arguing (1) that Hans Kelsen’s theory of the basic norm is best understood as saying that a person may choose to presuppose the basic norm in order to interpret the actions of legal officials normatively; (2) that H. L. A. Hart is best understood as espousing a sui generis view of legal normativity; and (3) that Hart’s view is preferable to the rather popular view that law makes some sort of moral claim. I accept (1) but think it is rather trivial. I find (2) plausible but the view itself problematic, and am therefore skeptical of (3).