It doesn't seem like you've actually read the article in its entirety, then (I can't blame you, it was very long but also very well written).
The author addresses 1) the counter-argument 2) an explanation for the "angle" wording (the section with the diagrams) which did a much better job of explaining the purpose of the angle than the "px is a non-linear angular unit" article, and 3) a line-by-line reasoning for why that other article was confusing (or outright wrong).
All of these sections made more sense than the other article, and in fact established why the points made by the two articles are very different and why it would make no sense for the px unit to be either "angular" or "non-linear".
The author addresses 1) the counter-argument 2) an explanation for the "angle" wording (the section with the diagrams) which did a much better job of explaining the purpose of the angle than the "px is a non-linear angular unit" article, and 3) a line-by-line reasoning for why that other article was confusing (or outright wrong).
All of these sections made more sense than the other article, and in fact established why the points made by the two articles are very different and why it would make no sense for the px unit to be either "angular" or "non-linear".