Remember, most of what you see today is restoration of what was there in the past.
The San Francisco earthquake of 1906 caused a lot of damage.
The above image from National Park Service
Old Russian church at Fort Ross, California, October 27, 1929:
The stockade walls ,as we see them today, were not yet built. The material for their construction is laying on the ground in front of the church. From FortRoss.Org
After the fort became a state park, the stockade walls were restored a
portion at a time. In 1929, the east, south, and part of the west
walls were rebuilt.
Later image showing stockade in place by 1957:
The park, as it exists today, didn't exist when the road was constructed.
I believe they were both constructed(reconstructed) at about the same time. A 1930 California road map, viewable here, shows a road in place. Considering funding bills passed in 1912 and 1923, planning and locating the roads route had to have taken place well before the stockade was built(rebuilt) beginning in late 1929.