In this context I'm not sure what "startup" is supposed to mean; but companies are fully capable of building up new cities if it makes economic sense. See https://en.wikipedia.org/wiki/Company_town. Disney was famously looking to run his own nuclear reactor so it is easy to imagine a private company doing fundamental nuclear research even if it isn't part of the nuclear industry.
They built a gosh darned city... oh wait, I was wrong, they built three. It was run like an extremely high-value military project, which is exactly what it was. Sure it was more theoretical than other military projects(at the time), but that is the game sometimes.
I get the sense that some folks just think "faster then we would do it now" is the same as startup. Which, to put it politely, I strongly disagree with. Startups are great and I am grateful for the daily value adds to my life, but pretending everything "fast" has startup mentality is just missing the mark.