You really have to laugh at that website. You would think for all those
supposed underground entrances and facilities, the author would show
one, just one, actual photograph of the area other than a fuzzy USGS
sat photo. I've been plenty of places in the desert with roads to
nothing of interest. For instance, there may be a mine claim there, but
that is about it.

Tehachapi and nearby areas have radar cross section sites. Thus far,
that's about it as far as spook stuff goes.