It seems to me that Vendors have very little protection from people illegally distributing their creations, as copyright notices do not stop criminals such as this site selling ones merchandise illgally, for sure DAZ, Renderosity, DNA and other marketplaces should be able to use the law against this site as it is reselling stuff without a licence which is held by these marketplaces.

I guess you will never stop people passing stuff bewtween each other as these are virtual items, but one can make it difficult, especially when as you say someone is actually reselling stuff.