I think you’re missing the point. It’s the policy itself that’s in question here. Just because they’ve been getting away with it since they put the policy in place and it’s been years doesn’t make the policy correct or not monopolistic.
You already admitted in a previous post that the policy of requiring app review didn't qualify as antitrust: "the practice of reviewing apps itself is not intrinsically harmful." That's your own quote. And I'm sure you know that MS has rules and policies to control what games are available on their own Xbox consoles. Can you name some gaming apps on the Xbox that aren't in compliance with Microsoft's rules?