Tracks, equipment and money are limited. Yeah, sure, if UP wants to add additional passenger train runs to Reno and Amtrak or Caltrans/JPAs have extra rolling stock and extra money, then just add more trains. But that's not the case. UP wants to limit the impact of passenger trains on its own operation, Amtrak (at least its management) wants to put its resources into services that have higher passenger loads and lower costs and Caltrans (and the JPAs) wants to spend its budget effectively. I doubt Caltrans cares about the CZ, except to the extent its unreliability impacts Capitol Corridor operations, but changing the CZ – break it up into a daily Bay Area to Reno corridor service and a less than daily Reno - SLC - Denver tourist service, for example – would help all three organisations meet their goals.
Anderson's testimony was vague regarding details, but the overall strategy was clear: redesign Amtrak service to meet the needs of the 21st century, rather than trying to preserve the ragged remnants of the 20th. He's right.