What would probably happen between 1 and 2 is that archive.org notices spike in traffic from Wikipedia, talks to Wikipedia engineers, they find out who is generating all these requests, and block them from editing Wikipedia.
Though it's certainly possible to generate enough junk edit traffic to cause disruption on Wikipedia, but that's nothing new. It's the nature of Wikipedia as the resource - it trusts the internet community to be good on average. So far it worked.
That's still not a DDoS, as its missing the Distributed element. Almost by definition if you can block all requests at source its not a DDoS, its just a regular old DoS.
1. Get Wikipedia to send lots of requests to Archive.
2. Archive blocks requests from Wikipedia.
3. Wikipedia citations are disabled.
In other words getting Wikipedia to DDoS Archive, so that Archive's defense hurts Wikipedia.
A very silly scenario of course, just coming up with one for why an attacker might want to indirectly DDoS Archive via Wikipedia.