As far as I can tell, Apple's new guidelines wouldn't let them put that app in the App Store anymore. Apple's guidelines say you have to sell through the app using their API and can't sell anywhere else. And you can't link to a place where customers can buy your service outside of Apple's control.

They can sell other places, but not promote those other places within the app.

They could offer their subscription on their web site and collect 100%. Their app would then be required to offer the same subscription deal as an in-app purchase for the same-or-lower price, and then they would collect 70%. The app could not refer users to their web site for purchases.