My understanding of his reasoning is that he does credit Musk with knowing things about thermal expansion, and it's precisely that combined with the hand-wavy treatment of it in the proposal that makes him believe that the whole thing is likely to be snake oil.

He's not really trying to have a reasonable argument, he's describing his thought processes around whether this is a project that is worth him getting involved in. There are a lot of bad ideas out there, and geniuses (if that is what Musk is) are no stranger to them (c.f. Einstein's wing design).

It's perfectly reasonable when faced with a huge number of proposals that take a significant amount of effort each to make an initial determination based on surface details. Sure you'll have some false negatives, but you'll have a bit more time to address the ones that really have a chance of going somewhere.

"Snake oil" is a term to be used when describing someone selling you something you don't need, and knows it doesn't work. It claims that it will fix a problem you have, but in the end the result is to part you from your money.

This is not "Snake Oil". This is a design, and one that is open. Elon is not asking for money for the idea, he's wanting engineers to help design this thing and have an open discussion about it.

Or, perhaps he just wants to derail the high-speed rail proposal.

I thought he handled that quite well, he specifically noted that his handling of thermal expansion was correct on the small scale.

Note that he mentioned that all of the renderings were correct for three pillars, but did not take into affect what happens when you expand to several thousand of them.

I would expect a rocket engineer to understand thermal expansion in an item that is 100 feet long, but I wouldn't be surprised if they did not understand what it was like when working with a 300 mile tunnel.

The principle of charity says one shouldn't fault other people for not following the principle of charity ;-)

Haha, funny, but that requires an addendum: 'provided there exists an explanation for their having abandoned it'.

It seems like many people are making this thermal strain criticism of hyperloop, is it possible that the critics are posting link-bait? I only say this because few are contributing new ideas, and most are writing with substantial amounts of vitriol.

Does Musk actually design his rockets? I thought he was in charge of funding them.

No, that's not accurate. His stockholders and/or venture capitalists do the funding -- remember that "funding" means answering a relatively simple question about risk versus reward. Someone still has to manage projects, make technical decisions. That's what Musk does.

Consider a parallel example -- Steve Jobs and Mike Markkula. Jobs made product decisions, Markkula funded them.

You are mistaking (part of) the startup world with how the real world works at large. (And to be clear, I'm not pretending that Elon has not made any direct technical decision; that, I don't know)

So that you get a sense of what can happen in the wild world, let me copy past wikipedia for you: "As of May 2012, SpaceX has operated on total funding of approximately $1 billion in its first ten years of operation. Of this, private equity provided about $200M, with Musk investing approximately $100M and other investors having put in about $100M (Founders Fund, Draper Fisher Jurvetson, ...)."