He means that HW2 is a unique case, and that a game releasing on Steam (such as this game in question) wouldn't likely contain a WinStore key in a physical release. So less keys floating around ready to be discounted.
Ok. Thanks for clarification.
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The whole UWP != Same build thing is dependent on how the developer chooses to make their application. You can have UWP apps/games as one project, or as separate projects connected by a shared project. UWP is just a set of APIs that are shared across MS devices, and each platform (PC, Xbox, Mobile, Holographic) has unique APIs that are specific to it's platform. The shared part covers a lot of what developers (of all types, not only game ones) use. So there would be a lot of reusability of code. Shared way on how to use storage, shared api on networking, shared api for all input devices (mouse, keyboard, controller, touch, pen, dial), etc...
So yes, you can have ONE project with ONE build that adapts based off of the device you are on (including console), it is also likely that you can have different projects that have different builds for each device. So PC, Xbox One, Xbox Scorpio, can all have different builds if the developer wants to, or they can have it as one project with one build. It also depends if the developer is using middleware and how the middleware setup their use of UWP. UWP in itself just helps with developers not having to rewrite a lot of code for each platform because of the redundancy, but there will always be platform specific code, it's just that a lot of it can be shared and using the UWP to benefit the developer so that they don't write as much platform specific code.