That's always what I wonder when it comes to MS's embracing of Linux... I hope it's not the case though. All they really need to do is get exclusive rights to it and then start suing all the other distros. They have enough power to do that if they wanted to. They just need to lobby the government to make IP law changes that make it possible.
They can't do anything against open-source licenses. That would almost imply launching a war worldwide. You have no idea about the implications.
And that said, we'll have to define what Linux IS exactly. Is that just the Linux kernel? (I think the kernel is all we could formally call Linux actually?)
The kernel itself - there's no way MS can ever lobby anyone to get rights on that. No f*cking way. Again if they try, they'll be up against something big.
Now they could of course use the Linux kernel, and design a whole OS around it as they see fit. A bit like Google did. Is that Linux? The kernel is. The OS, we can't call it that, and Android is pretty different from any Linux distro...
If they used the Linux kernel, they would have to add tainted modules all over the place to pull off the nasty tricks they do with Windows, and some would still be pretty tough to implement without modifying the kernel itself, which would have to be shared. No way. And anyway, would that still be a "Linux" system? Even less so than Android.
They are just playing with words here, and the hype. Maybe also trying to make all the less savvy crowd hear "Linux" from their own mouths, in hopes the crowd won't be tempted to go see elsewhere. Just occupy the field, you know. "Oh you guys are comtemplating switching to Linux? That's not very nice. But look, we'll give you Linux!"