Incidentally, Dave will know who deleted it because he has access (of course) to all the relevant logs. I presume Eric does as well?
Can someone (who has a chance of getting a response from him before the end of the universe) ask either of them? I really want to get to the end of this story.
Pretty sure the modadmins don't have access to such information. Only Dave would know. As for someone contacting him "who has a chance of getting a response from him before the end of the universe", I'm unaware of any such person existing. Dave ignores the moderators all the time, and I don't know how to get him to respond to any inquiries. I'm still trying to get him to take away my mod powers, but he ignores me. You are welcome to email him and ask him yourself, but I'm not too optimistic about either you or anyone else getting a response.
The one thing that might get his attention is if someone starts a thread here about a problem with the Atlas, then ambushes him with the question at hand. E.g., a thread titled "The 1872 Virginia results are wrong", and then the actual thread is about "Please tell us what happened to the French election thread. Also, when will you take away Morden's mod powers?"