It is possible for a "technical document" to appear rigorous enough to untrained eye, but sadly, you can fool people, you cannot fool nature. Which is why "Hyperloop", which was not even an original idea, still remain in paper...
AFAIR the paper was technologically sound to the first approximation; the objections were mostly economical (I'm ignoring people who missed that Hyperloop was not a vacuum tube design and went on ranting how infeasible it is).
Also, for a paper-only design, there seem to be plenty of activity involving people building actual hardware to test components.
Also2, from the first day it was known that Elon is not going to pursue Hyperloop himself any time soon; he threw an idea for others to pick up, and didn't promise anything. Judging him by not having built the Hyperloop by now is... insane.
