how are "springs" and "cushioning" supposed to provide long term, stable and robust support against the pressure of high-energy plasma from long-term multiple fission reactions? Any spacecraft actually built by human beings has a VERY finite lifespan before having to be discarded, or (in the case of the Shuttle) completely refurbished after each flight. This is supposed to be for longterm interstellar, or at the least, interplanetary voyages. How can these guys claim that what might have worked in tests, and what might be feasible in principle, would actually be viable over a long-term hammering of incredible ferocity?

"Springs" and "cushioning"? You have to be kidding. Don't springs, "cushioning", or any other structure for that matter, suffer from eventual fatigue and degrading? Of course they do, in the real world. How long would this design work then before catastrophic failure? Seconds .. minutes .. maybe weeks?

You made a flat statement 'it would have worked'; but can you or anyone else really answer these objections?