The methodological debate in Economica took place in the context of the larger political controversy over the role of the state in the economy. Hayek was on one side, Keynes and socialist planners on the other.
But Hayek subordinated his methodological arguments to his political bias. That is the source of his inconsistency. In the Economica, he attacked scientism. But after World War II, when the communist threat became more acute, he overcame his methodological qualms and became the apostle of market fundamentalism — with only a mild rebuke for the excessive use of quantitative methods in his Nobel Prize acceptance speech.
Because he was fighting communism, a scientific theory that proved that market participants pursuing their self-interest assure the optimum allocation of resources was too convenient for him to reject. But it was also too good to be true.