Ballmer's grandstanding. I'm pretty sure he understands the numbers in Amazon's 10-K filings.
Amazon made $745 million in income from $74 billion in sales last year, for a net income of $274 million.
That even seems understated, because they're obviously spending way more to expand their capacity than they need for just supporting their current operations. Last year, they have a net cash flow of $5.5 billion from operations, then spent $ 3.4 billion on purchases of property, equipment and software. Even after spending that much geared towards growth, that still leaves $2 billion in free cash flow to spend.
Let me put it another way, Amazon's net worth (assets minus liabilities) has gone from $17 Billion in 2010, to $23 Billion, then $27 Billion, now $33 Billion end of 2013. You don't do that without being profitable each year along the way, regardless of what they decide to do with the profit, which is clearly currently to reinvest the cash in order to expand quickly and grab as much market share as they can.
Ballmer's just jealous that no matter what Microsoft does or who they purchase, they can't convert their windows/office cash cows into a worthy reinvestment, because they're essentially out of new ideas, having mostly missed the ground floor of the Internet revolutions. So Microsoft's best bet is to act like a mature company and pay dividends so their stockholders can use that money to invest in something like Amazon.