Also, I wonder what HSR incidents he's referring to. The Spanish relatively low-speed human error crash? Systems like Japan's Shinkansen have never had a fatal accident, despite operating at the edge of technology for 50 years. I don't think a derailing accident is at all likely on a modern system like California's plan or the UK's HS2.
If the tube bursts so wide that the capsule could be ejected from it, the inrush of air would likely be so great that capsules probably wouldn't even make it out. The bigger concern would be that they could decelerate too quickly.
Interesting. No comment on the potential outcome of a passenger-filled capsule being ejected from a burst tube on high pylons at 350mph.