To truly support Open Source, they should show a willingness to work against Software Patents. The essence of Open Source is the freedom for anyone with a computer to turn their imagination into code. MS remains one of the biggest obstacles in that path.
Instead here is what they do:
1) Directly attack the Linux kernel in Android through patents
2) Sell patents to trolls like Intellectual Ventures, and directly fund them via investments
3) Support the cartel called BSA, which includes other luminaries like Oracle (http://www.bsa.org/about-bsa/bsa-members).
Honestly, say what you will about Google, but I can't imagine them ever threatening another software company with software patents.