The part of the TOS about posting ONLY your work (unless given permission) applies to all postings.  Nowhere does the TOS state that images can be posted without permission.

Anyone posting an image of someone other than themselves is supposed to ALWAYS get permission first. Renderosity generally assumes that members have gotten the proper permissions first--since that's explained in the copyright section of our TOS; however, we often require members send us a signed copy of the model permissions if nudity is involved.

We will also require the model permissions if we have any reason to believe that the post was made without the models' permission (nude or not).