Sorry, where's the assumption it's using kubernetes coming from? All I see in the response is nginx which doesn't imply anything k8s. The blog linked from the page doesn't mention k8s either (nor nginx).
That said, you can run an ingress for a service that's just an externalname reference with the right annotations depending on your ingress controller and I'm pretty sure it'd just work.
I think both commenters said those things in jest referring to the oft occurring on HN criticism that everything has to run on k8s nowadays, even a simple website.
That said, you can run an ingress for a service that's just an externalname reference with the right annotations depending on your ingress controller and I'm pretty sure it'd just work.