This article confuses recursive servers and root servers. K and I are authoritative root servers, and only respond with delegations to the appropriate TLDs (or error codes). DNS4EU is a public recursive service, like Google and Cloudflare. DNS4EU may have other issues like the referenced article suggests, but the article is conflating different DNS roles.
Something is off regarding this site. [1] I can't even connect to it. I tested with TestSSL and it says the server is likely gibberish. TestSSL does get something that matches SSLv2 and SSLv3 but that should be disabled in most browsers. Qualys refuses to connect to it "Assessment failed: No secure protocols supported". The site owner needs to resolve this.