You are giving the homeless man something for nothing, so that is ludicrous.  Since you are the giver, its up to you, what you give.

Here, renderosity is the "giver" the supplier of the gallery.  Therefore technically, they can ask for what they want in return for those services.

Renderosity is free to join, free to post to the galleries and get feedback, and free in forums as a resource to an artistic community.   I could see such arguments debated hotly over a subscription say, that is paid for on a subscriber basis, but it is hard to contend with things that are free.

Would you argue with a provider who gave a freestuff texture because they didnt want it used for commercial use?   Would you argue with a freestuff provider that told you not to redistribute the dress they gave you for nothing?

Again, i agree, and am sorry that some of the meaning behind some images is curtailed in cropped thumbs.  I do agree to that, that often, the theme or nuance cannot come across.  I would assume, since you have been here quite a while, you have a veiwing base, and collegues here that know, and appreciate your work.  They too, following the same rules, I don't think would think you are "cheating them" with a thumbnail.   I know I don't.