Too little, too late!
If Ballmer thinks that Microsoft needs a mobile strategy then why didn't he set on up when he had the chance? I think this is a poor display on his part: it's always easy to comment on something with a little hindsight.
Yet when he was in charge he didn't exactly do that well either. Or was the enforcement of a mobile platform onto the desktop market (Metro, ugh, yuck, blech!) his idea of a mobile strategy perhaps?
With strategies like that, who needs competitors? ;-)