No. Even ignoring UP/BNSF's reaction to the prospect of running passenger trains of any kind on some very heavily used freight track that's already on its way to double track wherever it can be squeezed in (hillsides are steep, and tunnels old and expensive to daylight or widen).

The current Tehachapi line was designed in the 1800s when trains moving at 20 mph on a hill were fast. Most of the west side is limited to about that speed (maybe 25) due to grade and curves. Straighten out the curves and eliminate the loop, and the grade (around 2.2% now) has to get steeper, which is impractical for a freight line.

HSR (any HSR) in mountains (any mountains) requires lots of tunnels, bridges, and steep grades to work. You have to keep the speed up, even if it's not 220 mph. A train powered for 220 on the flats should be able to maintain 150ish on 3.5% grades if the curves (horizontal and vertical) allow that. They could probably handle grades close to 5%, but would lose a lot of speed going up and be hard to control descending - so you have to be reasonable. Look at the Spanish lines for an example (lots of Youtube videos).

I do have to laugh at them hitting the cement plant, though, with the first try at an alignment. It's not as if nobody knew it was there, for 100 years or so.

Yes, there are wetlands in the desert (not just the Mojave). They are often just small spots (often on an active fault) where water is close enough to the surface to produce an oasis, but sometimes are larger. For that matter, a lot of the "dry lakes" aren't actually dry - they can be pretty muddy just below the salt-encrusted surface, as mired off-roaders and frustrated Bonneville speed-record hopefuls can testify. There's also groundwater in the desert - where do you think people get water from who live there? There is even a company that wants to pump water from desert valleys and sell it to LA. Didn't the T&T cross a "dry" lake or 2 that caused problems?