a) Locking a platform people hack afterward isn't really locking
b) None of those are X86. It's easy to lock down a proprietary hardware with a proprietary OS. It's virtually impossible to do so with X86 lest you risk platform incompatibility. I very much doubt Intel cares who wins the OS wars, as long as they supply the ammo.
Fundamental shmundamental. It is compatible with Windows binaries. It is compatible with Windows UI. Save for the logo on the back, it's open Windows. It walks like a duck, it quacks like a duck. It has the Windows Application base, and compiles and runs Windows IDEs. If I don't like Nokia's messaging app, I either switch or develop my own.
Also, it matters not if it's open Windows or Microsoft Windows. You should expand your understanding to platforms and ways of doing things outside the normal purview.