Because the state has no business annexing anything.
Discussion
That I agree with!
But in this specific context, the State is being invited in by a private citizen, in return for personal and property rights enforcement. A less-objectionable nation-state intrusion is difficult to conceive.
This might be among the least-wrong fiat laws passed by a modern State. :-p
Compare and contrast with the USA's "Contiguous Zone" and China's "Nine Dash Line"...