I suspect those are factors as well, but I think we're both trying to make sense of the timeline. I came to OpenStack after the dust had settled. The stories I've heard focused on how exhausting the process of getting NASA approval to open source Nova was. I can't see all of the NASA contributors being motivated by $$$ money. It seems NASA wasn't configured for continued stewardship and for their hackers to keep on hacking.
A point of correction, NASA Nebula became OpenStack Nova and one of the spin-offs was Nebula.com which folded and some of the team went to Oracle. That Nebula is completely different than (the European) OpenNebula: https://en.wikipedia.org/wiki/OpenNebula
But my understanding is that the European OpenNebula grew out of some of the same initial NASA Nebula code, and some folks went to the US subsidiary they created.
Now, while I was paying attention at the time, I didn't exactly have a front-row seat, and my memory could be wrong - three open source projects and three companies all with near identical names is a bit confusing!
A point of correction, NASA Nebula became OpenStack Nova and one of the spin-offs was Nebula.com which folded and some of the team went to Oracle. That Nebula is completely different than (the European) OpenNebula: https://en.wikipedia.org/wiki/OpenNebula