I think what they meant is that with decentralized DNS, it is possible to replace certificate authorities by using DNSSEC + DANE RFC6698[0], but I agree the way it's mentioned is confusing.
Replacing cert authorities with something DNS-based (or alternative decentralized DNS based) doesn't actually seem relevant to the problem they are highlighting, of sci-hub's DNS records being removed by private or government actors making it harder to find sci-hub... no?
In what sense is DNSSEC decentralized? IMHO signing the root zone is about the most-centralizing thing that has ever happened to the Internet.