The part of US-101 from Kings City to San Miguel that you describe *IS*
freeway and posted at 70 MPH. There is a new freeway section around
Mojave that is posted at 65MPH for no good reason that I can determine.
It should be 70 MPH under current law (and dereg under common sense).

Back in 1995, the California Legislature passed the existing 65/70 MPH
law with only about 2 decenting votes! I wonder if we should start
working for 130 km/h (81MPH) or dereg on rural freeways. Has anyone in
California actually been cited by a CHP for less than 85 MPH in a 70
MPH zone lately?