I figure how Elop pitched himself was "Let's try something crazy, and hey, we always have a plan B, I have an in at Microsoft." CEOs may have significant power, but they can't just sell the company with no buy in from major shareholders.
99.52% of votes were cast in favor of the Microsoft acquisition at Nokia's Extraordinary General Meeting on November 19, 2013.
But that's not what makes this a friendly takeover, because shareholders also have to approve hostile takeovers. This acquisition is a friendly takeover because the Board is in favor.