I think Mouse is just in love with the Tejon Tunnels route - in fact, most likely with the napkin-sketch route along I-5 that was assumed in ancient days (and later was taken up by M. Musk and his Hyperloop scheme). The fact that real world transportation needs would not be served by the simplistic straight line isn't relevant. Though trying to conflate meeting real transportation with CAHSR even as it has evolved is kind of difficult, too.