I think the thing that was referred to as a "fork" was the docker image, which uses the package you mention, and afaik is the primary way that people are receiving that package and believing it to be blessed by the Alpine gods. In the sense that the container is a distribution in its own right that deviates from the roadmap of the Alpine makers, it could be considered a fork of sorts. And given that the package naming is far less confusing than the dockerhub naming, I feel like that's what most people on HN are attributing the confusion to.
Note that the article doesn't mention that it's the container that is the source of confusion until the very last section, where it points out what they want to rename. The package itself is called alpine-pkg-glibc and as the author of that package has pointed out, the reason it is called that is to follow alpine package naming conventions, and they have mentioned on this HN convo that they are completely open to changing that name if asked.
But regarding the docker image, I'm well aware that this isn't technically a full fork; I was mirroring the language used on the parent poster - however, since your clarification does not do justice to the complexity of the situation either and implies that you have less clue about what you're talking about, maybe tone it down a bit. Especially since one possible solution to this situation is indeed for the frolvlad/alpine-glibc authors to produce a full fork of Alpine linux with glibc and call it something else (I wonder if Himilayan Linux is available?)