My reasons for regarding libertarianism as conservative run deeper than that. Libertarians serve the state all the better because they declaim against it. At bottom, they want what it wants. But you can't want what the state wants without wanting the state, for what the state wants is the conditions in which it flourishes. Silly doctrinaire theories which regard the state as a parasitic excrescence on society cannot explain its centuries-long persistence, its ongoing encroachment upon what was previously market terrain, or its acceptance by the overwhelming majority of people including its demonstrable victims.
Libertarians render a service to the state which only they can provide.
If it seems contradictory to say that coercion is consensual, the contradiction is in the world, not in the expression, and can't adequately be rendered except by dialectical discourse. One-dimensional syllogistics can't do justice to a world largely lacking in the virtue. If your language lacks poetry and paradox, it's unequal to the task of accounting for actuality. Otherwise anything radically new is literally unspeakable. The state commands, for the most part, only because it commands popular support.