Windows is just a little too different for them to make a proper purge of the project right now. Having Windows support is just a much larger cross-cutting concern than a Unix-like OS, which appears to be the only category of operating system they're currently supporting.

Windows will probably get a port some time later on. Remember that OpenSSH's libssh also has Windows support. It's just not something that fits in their current short term goals of fixing up OpenSSL (I like the term flensing they're using).