They have a very long history of playing dirty. Lotus learned it, MS took information Lotus shared with them and then shared it with Excel and Office and they supposedly kept Lotus on an API changing treadmill. Digital Research learned it, MS wrote code that made Windows 3.x crash if it detected DR-DOS. Netscape learned it. Arguably, IBM(OS/2) and any other operating system vendor learned it in the 1990s as well, MS charged premiums if hardware vendors wanted to install non-Windows operating systems. They sort of tried to do it to Intuit, they made a competitor and then effectively gave it away for free. Enough so that a lot of folks avoid Mono like it's, well, actually mono. They've established that reputation, and most of the time, by the time it became clear what was going on, MS had already done irreparable damage.
It is kind of embarrassing for Google, but if it is real and it continues, it's better to address it now rather than after MS becomes a titan of search and Google's market has eroded. At times, it seems like MS has changed in ways, but fundamentally they're still run by the same guys. Remember that when you play your Xbox or use Bing or any MS products, they don't like to see other successful software companies.
Also there's the strange fact that Bing and their whole online division makes gigantic losses. They're not in it for the money, they're in it to stifle competition and hold back progress so they can milk their cashcow some more.
They played dirty with Netscape/IE in the 90s and look what happened.