not necessarily specifically to modded content of existing resources.
Merely "resources for modders" not necessarily public domain, nor necessarily the other license you have. =)
EDIT: Specifically, a modders resource might be a composite of two other resources, or, a resource for which you created the model, entirely, but not neccessarily the texture, although the texture was specifically allowed to be used in this way.
Its more complex than you might think.
Also, on that note, I find I do not like any of the licenses on texturu.org, so, as a result, i would not be using texturu.org, in any case, regardless. For example, I have a number of models which are entirely my own work. I will not be posting these there, as I am not fond of the licenses. =P
EDIT2: for example, most of these, I can re-license, freely, as they are my own work, or use public domain licensed textures. (not sure if the rare couple of models with gpl'd textures are among them, though, I'd have to check.)
http://ebonrai.com/gplart/These, i would not be licensing for the use of texturu.org, for example, as I'm not fond of the licenses. <g>
