No.
Your is a logical fallacy. You are assuming that the antithesis of the Austrian school is Keynesian. It speaks to the academic poverty of the economic field that anyone would resort to that argument as a rebuttal.
Economic theory that assumes systemic equilibrium is bunk because the assertion is mathematically false. Much more of economics is bunk because it is inconsistent with human behavior. Keynes was subject to these fallacies as well.