On one hand, Microsoft needs to figure out its future. Clearly, open source is going to play some prominent role in that future. It has to. Microsoft has no choice in that matter.
On the other hand, Microsoft has tens of billions of dollars to protect. So, whatever pretty phrases the company may say about Linux, interoperability, etc., Microsoft will do everything in its power to block open source and open standards. It has, in a very real sense, a fiduciary duty to try to kill it.