Thanks for posting this. We need to do better. I believe the submission circumventing several fail safes in order to remain for so long. This is my understanding of how it happened:
The submission was old, and the controversy around it was generated after its release, after we had decided to let it remain.
There is no real mechanism for re-evaluating old submissions. We make a call on the new submission and if it is accepted, we tend to forget about it.
The negative criticism that came later came in the form of comments, which don't flag a mod or admin's attention. If members had flagged or reported the content, it might have been re-evaluated sooner.
Our TF2 managers may be inactive, and/or a bit detached from the general TF2 community, especially ones elsewhere (like reddit and STEAM) and therefore may not have heard about the controversy from these sources. I only found this out because I regularly search reddit for the keyword "gamebanana".
Our reporting/flagging mechanisms require login, and perhaps this is a problem too, as people who want to just alert us to an issue cannot easily do so.