Reading between the lines this is about attacking the growth of android. It isn't in Apple's or Microsoft's interest to have Google Android steal their market from under them. Android remember uses the Linux kernel, and potentially is not the only mobile O/S that will be Linux based. Linux has a good track record in the embedded space.

Or put another way, if Google is going to rule the mobile: they would both like a piece of the action.

Whether or not it is true is a different matter, but it's plausible.