Willa writes "After the 1999 fire, the BLM came up to Mike Castro's southern boundary line (using highly accurate satellite fixes) and closed the road."
Willa, while being respectful of much of your other content, you are not correct in that statement. The road is closed well south of Mike's property line. Mike has taken the liberty of posting BLM land between the closure gates and his own boundary as his private property. The publicly-owned portion of adjoining Moss Mill also has the misleading appearance of being privately held because of the misplaced postings.
The closures occurred simultaneous with the replacement of Moss Mill Rd. by the circuitous route around Bowen Ranch. A GPS of the area will show that Mike's property is much smaller than his postings indicate.
(You can also check the locations of the closure gates on the latest WEMO map for verification of their location relative to the actual private property boundary.)