That's the only dichotomy that matters. An agency operating under the auspices of "the state" explicitly declares that consent is immaterial to their ends. No state, on the other hand, does not take this as the default position.
I believe it was Molinari who said:
Anarchy is no guarantee that some people won't kill, injure, kidnap, defraud, or steal from others. Government is a guarantee that some will.
But if you only look from the eyes of the dichotomy, you ignore the other possibilities. For example that an agency does not need to be "under" the state.
Also I don't see that declaration anywhere, sorry.
I don't understand what you mean. An agency not operating under the auspices of a state would, by definition, not be a state. Perhaps I'm not explaining it properly.
Under a state, a group of people - an agency, so to speak - exercises ultimate control of decision-making within a certain territory and supersedes any individual; they ignore consent, either implicitly or explicitly. Any other group within that territory either operates with the permission of the state government, or in spite of it. If the latter, they're still subject to the state government's influence. In other words, whether or not an agency is explicitly a state agency, they are subject to distortions to incentives created by the state.
By contrast, without a state, individuals hold ultimate decision-making authority.
Where this gets murky is the fact that individuals can transfer this authority to others in certain ways. For example, individuals can consent to forming a covenant community in which there are rules, regulations, and security provided by other individuals. However, this sphere extends only to those that have consented to it. That's where the ultimate authority lies: in those who consent.
This being the case doesn't prevent bad actors from doing bad things, but if the former is true, then individuals will violate the private property in accordance with state government rules and regulations.