The reason you can't redistribute the obj files is that they are copyrighted by someone else. In Poser, you don't create new models. You use models others created. If you're giving away someone else's work that they are trying to sell, what incentive does anyone have for buying it from the original creator? ODF created Antonia so he has the ability to allow redistribution of her. As far as the other sites you mentioned, make sure you check their licenses as I'm not sure they allow redistribution.

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