Know what this seems like to me? A kinda stupid and well disguised shareholder confidence booster. From the article, its also "Microsoft could decide to", "Maybe they'll do", "They could do", and from what has been described of UWP in this thread... Its not a huge deal. Hell, the article only says "Maybe they'll ensure things can only be sold on their stores". Its just... So much nothing.
What it does do? Any MS shareholder reading this will go "Oh, Microsoft has all these options available to control the market", which may raise confidence. If they're not a fan of the shadier practices, they have Microsoft's "We're being fully open" statement to fall back on, which denies all of this, and its such a minor bit of news in terms of who's reporting it that anyone who might be scared of public outcry is likely to understand 99% of Microsoft customers won't even know its happened.
Its especially suspect coming from a developer that's worked closely with Microsoft previously. It seems pretty unlikely they'd just suddenly spill the beans on this if they're actually still in the loop enough that they'd know, as then they'd lose the trust of MS and companies like Sony and such who also couldn't trust them to keep corporate secrets, potentially making it much harder for the studio to find partners to work with in the future, for a bit of seemingly fairly minor scaremongering.
I mean, hey, maybe they're just pissy another company is making Gears of War 4 and are just throwing mud, and Microsoft isn't involved behind the scenes, but the way its been reported... Yeah. Seems like a shareholder PR stunt. Sure, MS is pretty shit to its PC customers a lot of the time, especially gamers, but there isn't really anything at present that's confirmed as happening. I'll wait until there's a bit of confirmation that any of this will actually be the case before grabbing the pitchforks, and when it is confirmed, I expect several multi billion dollar industries to be grabbing some nice pitchforks too, as it'll impact them heavily as well [Well, honestly, ATM I'm not seeing how it would, but if it somehow did end up able to affect AAA titles, you can bet your ass EA, Activision Blizzard, Ubisoft and such would want a say in it].