It makes sense that individual ethics can vary within a natural law framework: the nonaggression principle isn't so much a rule to be applied as a norm to be followed. It's the foundation that makes life among other people possible.
Economists who have written on punishment find Rothbard's “double restitution” idea puzzling, because they think about it only in terms of economic efficiency. But Rothbard's theory is based on a moral principle.
It isn’t a good argument against Austrian economics that someone might come up with a science that made better predictions. You have to show us the science, so that it can be compared with praxeology. Suffice it to say that this hasn’t been done.
Rose Wilder Lane was one of the past century's most ardent proponents of liberty. Give Me Liberty, which traces her evolution from communism to a devotion to liberty, is as relevant to the present as it was in 1936.