Rigging data is not protected under copyright if it is determined by a settings within the program. Rigging can, however, be protected by a contractual agreement (such as a Eula) -- for example, the DAZ figures. "...an item derived from a BSD-like licensed mesh would be legally no different to what they do already." Yes, it would, as it would necessitate the inclusion of an alternative licensing arrangement to the license presently required -- to exclusion of others -- by Renderosity.

thou and I, my friend, can, in the most flunkey world, make, each of us, one non-flunkey, one hero, if we like: that will be two heroes to begin with. (Carlyle)