Depends how you define evil? If you mean they’re continuing to Linux in an effort to ensure it works well in their Azure platform which they can charge money for using, then yes?
They’re making all the right decisions though, they know that there is great demand for Linux in the server market, and are happy to allow it to run on their cloud platform to ensure viable competition with the other big players (AWS & Google).
Then in turn, their contributions benefit the open source community as a whole.
The fact they’ve also made .NET Core cross platform and another step in the right direction, as well as making VSCode cross platform too.
What would be nice is if they made desktop Office available. It’s one of the few subscription models that would probably work out well for them as many businesses would probably be happy to run Linux clients with native Office 365 support.