I don't think it's so much "sav[ing] face" as much as it is getting the message out they fully support open source.
The long term play is azure which is their big money maker. 1/3 of deploys on azure (IIRC) use linux images. Our startup got a huge credit to host on azure and we don't use .NET nor Windows. Competition is good.
Yeah, it's clear they're trying to "save face" in front of the open source community and become more developer-friendly (Bash on Windows too).
But I must say, ten years ago when I had to choose between Java and C# for a SCADA project I picked the latter because of the Visual Studio IDE which was already well above the competition (think Eclipse/NetBeans back then).
I'm glad they've brought it back for all open source software.