My suspicion: it's not relevant to the HN audience. DF is opinion pieces (mostly) about Apple. While I'm sure many DF readers use some Apple device(s), I suspect many (most?) DF readers do not care about "inside baseball"[0] for Apple.
[0] https://en.wikipedia.org/wiki/Inside_baseball_(metaphor)
Supporting a monopoly like Apple will sure attract a lot of detractors in a forum named "hacker news". The same would happen to Microsoft supporters 20 years ago.
Karma's a reflection of how much someone uses HN. Glancing at his account, it looks like he has never submitted anything before this article, and almost never comments. That account having low karma doesn't really tell us anything about him, beyond that he's not a HN regular.