In this instance I also agree with synonyspammer. The Palmdale/High Desert area will for many years remain a relative minor submarket compared to LA, OC, Inland Empire, and SD. Bypassing Palmdale speeds up trips to all those others in SoCal. Even if you discount SoCal-Norcal, there's still plenty of travel from SoCal to Bakersfield, Fresno, Modesto, and on to Sacramento, which for now doesn't have any direct rail service in the missing link. And while HSR may not capture a huge portion of SoCal-NorCal traffic, it will surely grab a portion (along with induce more travel), and thus time saved to 90% of SoCal's population may results in higher ridership than direct service to a relatively small (albeit primed for future growth) submarket.

I'll jump to anticipate your usual pulling rank and answer, no, I don't have access to modeling tool and data to prove that hunch, I'm not getting paid for that. It's just a discussion board, but common sense and observation of transportation around the world often suggests patterns. And that suggests the Palmdale detour is rooted more in politics than blind and neutral pursuit of the highest ridership. France, Germany, Spain, Japan, soon the UK, etc. would tend to run more direct and connect to side market services rather than pandering meandering, unless politically driven.

Caveat: I could be wrong. (But I also could be right.)