I love him but he was wrong. He conflates definitions with demonstrated behavior and this is an example of why he was ostracized for his dogmatic verbalisms.
His method of investigation, which he calls Austrian but is arguably Ukrainian instead, is reducible to the study of the means of improving the institutions that facilitate the voluntary organization of production by eliminating all possible frictions to economic velocity.
Whereas the mainstream is reducible to the maximum consumption that can be generated by interfering with the voluntary organization of production without producing the disincentives that would increase frictions sufficiently to produce results counter to the ambition.
When the differences between misesian and mainstream are one of morality and externality, not definition.
Mises engaged in fallacies throughout his work. He makes consistent mistakes in the application of aprioristic logic of axiomatic systems to the proximal logic of theoretical systems.
He discovered operationalism in economics just as Brouwer discovered it in math, and Bridgman in physics, and popper in philosophy.
But none of them managed to put their efforts together into an innovation in the scientific method and the formal uniting of philosophy and science into a single discipline; and finally retiring moral discourse just as moral discourse retired religious discourse.
This is perhaps one of the greatest failures of the twentieth century.
Mises was a little right. But his dogmatism ended both his career and his potential to solve the problem not just if economics but if the social sciences.