That's a good question. Originally it was Linux only as the EFS client was locked to NFS 4.0 and the Windows Server NFS client was 4.1 (why 4.1 is not backwards compatible, I don't know). However, the announcement mentioned using the PowerShell cmdlets to attach EFS volumes, and in fact the PowerShell help pages have specific commands for working with EFS. So, my guess is that it is now available for Windows and Jeff didn't do a very good job of bringing that to light.