If it can be found from portage, I believe, the permission to distribute the software is/was given to Gentoo, possibly to other major distros too, but bundling the software itself to any OS (inc. windows, os x) is forbidden? So, you can download and install it through portage (gentoo offering way of distribution), but not bundle it to OS, since that would need another permission from google..?
Edit: Though, it might be a great program for what it is, I don't see why it should be distributed with Sabayon. Once you've used it, most likely you will never touch it again, which makes it only waste of time and space..
Tux Klux Klan.