I'm not sure if you have any more options other than convincing him he made the wrong decision. Writing down evidence, like you did, is a first step, but ultimately he is the highest (and only) authority when it comes to closing Area 51 proposals. Sometimes, it works better if you can deliver your point of view verbally, so you could try an email him (his email is on his profile page) and see if he's in for a phone call or video chat.

I'm not sure if you have any more options other than convincing him he made the wrong decision. Ultimately, he is the highest (and only) authority when it comes to closing Area 51 proposals.

Writing down evidence, like you did, is a first step; I can imagine that when your point of view would have a lot of support here (maybe even from other Stack Overflow employees), he could reconsider his decision.

Sometimes, it works better if you can deliver your point of view verbally, so you could try to email him (his email address is on his profile page) and see if he's in for a phone call or video chat.