OK , Supersonic response from NG seems to answer my question pretty well
Thank you for your inquiry. Please be advised that royalty-free
license does not imply free use. The photographer still collects a
payment if the photo is licensed. In the RF model the publisher
makes a single payment purchasing a license for reuse without paying
As we have no exclusive contracts for any of our readers images, we
have to host them in the RF section. The downside is that we are not
able to offer publishers exclusive use of these images, but at the
same time photographers are free to promote and license these images
through other channels, as well as on our website.
If you are uncomfortable with your work being in the RF collection,
please let us know and we will remove the images at your request.