PB never said Tehachapi is seismic-free. Noplace in California is seismic-free; there are only degrees of risk. The programmatic EIR didn't, either, and had a fairly extensive analysis. Mainly an engineering exercise anyway - design to avoid obvious recovery problems (like tunneling through major known faults - San Andreas and Garlock for instance) and in general make post-earthquake recover as simple as possible.

If you're going to live in California, or build something there, you need to expect earthquakes, just like Florida has to expect hurricanes, and deal with it. No story here.