Well, if they deserve anonymity, they also deserve to be able to protect it, and they have really few tools against a doxxing, the DDOS was one of them, corrupting the archived article was another, albeit dangerous for their own reputation as an archiver.
The crux of the problem was the doxxing, not the defense against it.
You don’t think leveraging your site to DDOS someone is a problem?
Do people not also deserve to be protected from being DDOSed? Do people also not deserve to not have their internet traffic be used to DDOS someone?