My two cents: Microsoft is known for being unethical with its competitors, but never with its employees. Right now, Microsoft is in a position it can take a stand for what's right and refuse to complete the acquisition unless Skype aligns its HR policies with the company making the acquisition.
Microsoft is not paying 8.5B for the code. They are buying the Skype brand and the loyalty of its customers (at least the ones running Windows). What Skype is doing - and that's something that's hitting mainstream press soon - will damage the brand - and possibly customer loyalty - irreparably.
And, by provoking a diaspora of the talented people, they are creating dozens of competitors.