That means that LAUS is a "through" station, and, following Agency policy, needs to have track space for through trains to bang through at 220 mph.

This makes no sense. In Germany, ICE trains frequently use existing tracks between intra-city stations, and are only "high-speed" out on the open countryside. Thus they may start at an outlying station (i.e. Hamburg-Altona), then proceed to the main train station (i.e. Hamburg Hbf), may make one or two more stops within the metropolitan area before going onto an HSR track and proceeding at high speed.

There's no reason why Los Angeles Union Station would need to accommodate a train going through it at 220 MPH; under German practice, every ICE train would stop there - even those traveling through the station.