Microsoft have improved leaps and bounds in the last few years but saying that a story is immediately hyperbole because "X-good-technical-reason" isn't something I'm willing to commit to for any large corporation.
I appreciate the option of running other OS more open to explore the ideas of Xerox PARC.
Also Apple just got UNIX by acquiring NeXT, with Be the music would be other.
Even on NeXT's case, UNIX compatibility, was a means to allow software into the system, not out of the system.
No valuable NeXT application, or for that matter Mac OS/iDevices, made that much use of UNIX APIs.
It's not "more open" than C# and .NET in that regard.
Does it mean one could actually review code and fork theses languages too if need be?