In California, maybe this one?

21461. (a) It is unlawful for a driver of a vehicle to fail to obey a sign or signal defined as regulatory in the federal Manual on Uniform Traffic Control Devices, or a Department of Transportation approved supplement to that manual of a regulatory nature erected or maintained to enhance traffic safety and operations or to indicate and carry out the provisions of this code or a local traffic ordinance or resolution adopted pursuant to a local traffic ordinance, or to fail to obey a device erected or maintained by lawful authority of a public body or official.

The law that says disobeying officially posted traffic-control signage is a prohibited?

How does your average driver know that the traffic control signage is official when the residents are putting up their own privately owned signs for traffic control?

If they have to 'err on the side of caution', then the residents win, despite having no legal right.

I'm pretty sure there are laws against posting fake signs on government-maintained roads.

And yet here's someone proudly, in national media no less, saying he does exactly that...

A law that says "no thru traffic"? The real question would be "what law prevents that from being written into law". To which the answer is probably nothing.

Even having such a law preventing certain laws does little. There's a well-known top-level law stating a particular right "shall not be infringed". Infringing laws abound nonetheless, with most judges disinclined to invalidate them.

Alas if they'd only left out the word "militia"...

Militia had a specific meaning to the founders. Alas, if people today would study what the words they used actually meant.

Is there even treatment for unjustified feelings of superiority?