Quote - I'm not sure the policy was ever the official thumbs only. I believe that was just a guidance and assistance if you couldn't find a way to comply on your own. This is what I was lead to believe at that time.

No, the thumbnail had to be representative  of the image you were uploading. Meaning that if there was violence of nudity, you had to pick a portion of the actual image that didn't have any violence or nudity in it, and use that part for the thumbnail. If you didn't want to, or didn't know how, you had the option to use the generic Renderosity one. The reason behind that was continuity in the gallery.
I just looked at the gallery thumbnail policy again, and it states:

Quote - We will allow the Renderosity generic "Content Advisory" icon.  Just right click and save to your hard drive, then upload in the slot for your thumbnail. OR make a proper thumbnail that is representative of your image, but doesn't show nudity/violence

The only thing that I can think of  as to why you have been allowed to make your own generic nudity thumb is that they are no longer enforcing that part of the thumbnail policy. Which IMHO is a good thing because if I have the nudity filter on I'd rather see pretty thumbnails instead of pages of generic "Content Advisory" ones.

If that is the case I would like confirmation from a staff member that it's acceptable to make our own generic thumbnails for nudity and violence, because I would like to be able to do the same for some of my future uploads.
 

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi