Not surprising
Given Microsoft's recent track record of integrating companies they have acquired - perhaps the simply don't want the buzz going about a bunch of companies they have bought that might just fizzle like most of the ones that have gone the same path.
Microsoft seems to be still struggling with buying an innovative company without suffocating it. It will be interesting to see if they can resolve it - because a company like Microsoft which tends to suffocate internal innovation that lacks this capability cannot compete in the long term.