More palatable to investors, probably. It's harder to turn around and sell out when you've just been offering "open source" rather than truly free software.
They rather miss the point though, if they're concerned about democracy and politics.
It is both. But still the OS in the title plays with the idea of Operating System or Open Society among other interpretations. Read it how you want it.
I was actually referring to http://democracyos.org/ - it says "Open Source Join a community that's hacking the future of democracy today. We are 100% open source with an MIT license."