They mention the Computer History Museum. The version control history would also be interesting, from a historic and software development industry history. Whatever they may or may not have used back then. Of course publishing that is likely much less viable and possible due to different concerns.
MS chose the MIT license which is entirely free software.
I doubt adding a "no commercial" clause prevents the big tech companies from training their AIs on your material. They currently claim it's fair use to take any copyrighted content, regardless of the licensing.
