I wonder why they decided to run the ARM version of Windows though. If one emulates, does it really matter what platform to emulate? Isn’t Windows for x86 still quite a bit more useful (e.g. doesn’t have to run a second layer of emulation to run x86 apps)?

And it talks about "translating Windows code into ARM", and using a just-in-time compiler. It sounds like perhaps it's "compiling" ARM into ARM, because the original ARM can't be run due to Apple's restrictions.