Copyright laws can not have anything to do with it. Only God can claim copyright to persons appearance. In case of celebrities, you can even publish photographs you have taken of them without asking permission. Therefore, a 3D image that only looks like a celebrity can not cause any problems. I guess Gwendolyn has just done the same decision as many other artists: leave Renderosity because of the new TOS that attacks against artistic feedom and freedom of expression. For a merchant, it is even more important to leave Rosity, since more and more people are joining the boycot against merchants and products marketed at Rosity.