2) I did not claim Levy is a transportation engineer
3) Musk did this quite handy, he did not propose the hyperloop in a vacuum (pun intended) but for a specific application, this increases the chances of something being done with it
You have to start somewhere, think of this as a first proposal that can be suitably amended or scrapped in its entirety as more insight is gained.
I'm pretty skeptical about the whole thing but Musk has a history of pulling off impressive feats and I would not put it past him to come up with something that might work when tweaked. So let's hear it for constructive criticism (fix what is broken or provide actual proof why it can not work) rather than outright dismissal.
But from that perspective conventional HSR is easy and cheap, too. You could sketch out a reasonable LA-SF HSR system with optimistic assumptions and put a $15 billion pricetag on it. It also has the benefit of being technically validated, and implemented in practice: Japan, France, and China have all built working systems for per-mile costs in that range or less. The California HSR issues have more to do with a mixture of politics and the U.S.'s "unique" regulatory setup, and it's not clear how hyperloop plans to sidestep those, even assuming the technology works exactly as envisioned. If Musk has some secret on how that's going to happen, I'd like to use it to just build conventional HSR!
Put differently he seems to be offering a technical solution to a problem that didn't have a technical bottleneck, and it's not even clear the technical solution works.
I did not claim Levy is a transportation engineer
You at least very strongly implied it. What did you mean his agenda was then, if he isn't a transportation engineer? If his agenda was that non transportation engineers should mind their own business, why would he be commenting on the math and engineering of it? That's not a coherent reading of what he said.
Alternately, the proposal could have avoided making detailed claims on cost and routing, and instead focused on the high-level technology, more in the direction of validating the basic idea, and leading up to a test track. There's nothing wrong with that. But if you're going to claim you can build a line on a specific route for a specific cost, you need to do the work to justify those numbers credibly. Musk's existing document, at least, comes off as very hand-wavy and lacking in empirical grounding for any of its detailed engineering and cost estimates (that grounding could be rooted in his own data, or in existing data, but there has to be data somewhere).