TechCrunch wrote[0] "This feels like a sign of goodwill on behalf of Microsoft, which closed its acquisition of GitHub last October, with former Xamarin CEO Nat Friedman taking over as GitHub’s CEO." I believe it's more of a sign of an attempt to kill GitHub's rivals by hurting their revenue streams. As Aaron Levie, co-founder and chief executive of Box once said in 2014, “These guys will drive prices to zero, [...] you do not want to wait for Google or Amazon to keep cutting prices on you. ‘Free’ is not a business model.”[1]
[0]: https://techcrunch.com/2019/01/07/github-free-users-now-get-...
[1]: https://www.nytimes.com/2014/08/25/technology/box-dropbox-an...