The linked homepage says this icon theme is GPL. The linked deviantart page never loads, but regardless the one at xfce-look is not an exact copy, but derived, and can thus impose terms on top of the original public domain work.
I don't see GPL anywhere in the icons-xfce-gant-3.9-6 tarball. It's common for xfce-look.org page to list invalid licenses if the author was lazy to change it to correct one.
What is the basis for claiming this icon theme is public domain? If there is no license at all, then it is straight-copyright, and nobody can redistribute it at all. The only claim I see to *any* license is the GPL selection... The author's selection of the GPL, even if out of "laziness" is at least a valid argument to claim he licensed it under those terms (thus permitting redistribution). Otherwise, we have nothing.
The GPL requires to be distributed together with the work. This is not the case, thus this is not licensed under the terms of the GPL.
The original gant icon theme the xfce gant icon theme is based on was distributed with public-domain license when I committed this ebuild I bet you can still find the icon set from deviantart with the public domain declaration, but I'm not going to waste time on finding it *again* And nothing seems to indicate the license somehow changed from that
The GPL *cannot* require the initial party to do anything. I'm not disagreeing that your assumption is correct, but the current situation is undeniably legally ambiguous.
