I don't think Microsoft should block anybody or anything.
They're a great IT citizen. They support their Outlook.com users and other users on every OS under the sun.
Microsoft should point out that its open, cross-platform solutions are superior in usability and functionality to Google's closed, proprietary services -- and are available cross-platform.
Microsoft is once again the "safe" choice -- if you have a Windows Phone and PC now, but decide to go, say, BlackBerry 10 and iMac, your Outlook, SkyDrive and everything else will work with those platforms as well. Google is the dangerous, unreliable choice -- if you have Android, but decide to go, say, Windows Phone and iPad, your Google Services will degrade (or may stop working entirely). Or they might work okay until Google decides to make another spontaneous change that breaks everything.