The problem with Windows is that it needs to install a bunch of things like cygwin and other stuff.
Under linux it's just a matter of adding a dependency to the homegenie debian package (arduino-mk) that will be automatically downloaded by the package manager.
In windows there's no such "arduino-mk" package available, so it would require installing the whole Arduino IDE.
Unless you like the idea of programming Arduino from everywhere by just using a web browser, this is pointless since you already got the Arduino IDE on your Windows box.
Also what makes interesting having Arduino programming from HG in linux, is that linux is a portable S.O. that works on many embedded systems and so it turns the box into a "mobile" Arduino programmer.
Cheers,
g.