Now, Musk may have an answer to the issues, but he certainly didn't present them. The fact that there is no obvious resolution suggests that either Musk didn't think of them or he intentionally omitted the answer (both are damning)
No, thermal expansion criticism is not careful enough. See my comment:
When making an argument, sometimes it is good to make an assumption and then prove the assumption is false... sometimes it is just a straw man.
The tube will be supported by pillars which constrain the tube in the vertical direction but allow longitudinal slip for thermal expansion as well as dampened lateral slip to reduce the risk posed by earthquakes. In addition, the pillar to tube connection nominal position will be adjustable vertically and laterally to ensure proper alignment despite possible ground settling. These minimally constrained pillars to tube joints will also allow a smoother ride.
A civil and mechanical consulting engineer [1] who also has put some code on Github and writes a blog.
> Why does he feel like he gets to talk down to someone who has sent rockets into space, on the subject of engineering?
Probably because, unlike Musk, he actually has professional qualifications in the kind of engineering at issue on the points on which he is criticizing Musk's proposal.
[1] See, e.g., http://www.codeproject.com/Articles/582981/A-Coder-Interview...