Quote from Linus Torvalds:
Science may take a few hundred years to figure out how the world works, but it does actually get there, exactly because people can build on each others' knowledge, and it evolves over time. In contrast, witchcraft/alchemy may be about smart people, but the knowledge body never 'accumulates' anywhere. It might be passed down to an apprentice, but the hiding of information basically means that it can never really become any better than what a single person/company can understand. And that’s exactly the same issue with open source (free) vs proprietary products. The proprietary people can design something that is smart, but it eventually becomes too complicated for a single entity (even a large company) to really understand and drive, and the company politics and the goals of that company will always limit it. In contrast, open source works well in a complex environment. Maybe nobody at all understands the big picture, but evolution doesn’t require global understanding, it just requires small local improvements and an open market ('survival of the fittest').
We will try to use open formats and free tools like Mediawiki, OpenOffice.org, Blender, etc. If we use 30 proprietary tools, and each one costs $300, then our free wiki isn't so free for people to contribute to.
Free software has a critical mass of technical people working on it already, but not always the market share or the name recognition. In other words, Keith is sure that free software is better overall than proprietary software even though it might have 1/10th the users and so still have a little polishing left to do. Ferraris don't have AC or cupholders, and we shouldn't let a lack of polish get in the way of using some of the amazing free tools that are out there.
Strictly speaking, free software has nothing to do with a Space Elevator, but restricting ourselves to free software is actually a little restriction, saves money, lowers the barriers to having people help us, gives us better results, etc.
To believe that we can all work together to design the space elevator, but not believe that free software isn't a very helpful piece of the puzzle is illogical. We cannot share data unless we all have code to manipulate that data.
If anyone wants to know more, they should read my book After the Software Wars.