What do you mean? The Linux kernel could theoretically be available to Windows users. In practice, embedding parts of the kernel in Windows under the license provisions of the Linux kernel is something Microsoft is unlikely to want (which makes sense because of their business model). Note that a lot of Free software does run on Windows, so the problem is not about Windows as a platform.
This is not inconsistent with "user freedom is everything".
This is not inconsistent with "user freedom is everything".