Declaring oneself a constitutional county undermines the authority of officials authorized to act under the Constitution. I believe it ultimately subverts the authority of the Constitution itself.
When these resolutions instruct county police not to enforce certain laws, such as red flag laws that allow the confiscation of firearms from certain people, they violate Article 6 of the U.S. Constitution. Article 6 declares that the Constitution itself and federal laws are “the supreme Law of the Land” and cannot be overruled or superseded by state laws or laws at lower levels of government.
So any county that claims to nullify federal laws it finds objectionable raises constitutional problems. So, too, do assertions of a right to obstruct federal law or to impede the exercise of federally guaranteed rights and liberties.
In both scenarios, local authorities claim they are under no constitutional obligation to enforce, or to help state or federal officials enforce, laws and regulations that are, in their view, plainly unconstitutional.
...
Notably absent were concerns about threats to reproductive autonomy, sexual and gender identities, or public safety endangered by firearms violence. Professions of constitutional fidelity by constitutional county advocates are more often about politics than real concern for the Constitution.
Note this last paragraph (emphasis mine). Clearly these people are not truly concerned about Constitutional rights--or at the very least not all of them.
But what about legitimate issues? Suppose, for example, a fascist were to get into power, and attempt to force federal law enforcement to override state's authority on the matter of abortion rights?