Maybe for whatever reason this particular post is better than others? I put <<asahi site:news.ycombinator.com>> into DuckDuckGo. (Not because there's anything magic about DuckDuckGo search results, but to get a sample of Asahi-related HN posts without cherrypicking.) The first hit is to https://news.ycombinator.com/item?id=35394297; no trans-related things there that I can see either. (It does have some discussion of why the Asahi Linux site was turning away people coming from HN, and the reason given there was nothing to do with "Lina", nor with transphobia, but was that marcan feels that HN discussions of Asahi are full of mistakes.)
Second hit is to https://news.ycombinator.com/item?id=35928000. Again, nothing trans-related.
(To look for trans-related things I (1) skim-read the comments by eye and then (2) searched for "trans", "gender", "pronoun" and "man", the last because people being obnoxious about trans issues often can't resist going out of their way to call someone a "man" or a "woman" if they think they might be upset by being called that. I specifically kept an eye out for dead comments. It's very possible that I missed things, but it seems to me that a minimum threshold for saying that there's "constant transphobia on display" is that someone explicitly and somewhat carefully looking for it should be able to find at least one example.)
Next few links aren't obviously strongly-Asahi-related articles. Next one that is is to a comment about "Lina" somewhere in the middle of https://news.ycombinator.com/item?id=35233479, so I took a look at the comments there. There was indeed a "Lina" subthread, some of which was pretty rude but none of it in a visibly-trans-related way.
My general impression of the HN comments on Asahi-related threads, from this, is that they are on the whole very positive, that some people think marcan is weird for Lina-related reasons (which may or may not actually make sense; I have no knowledge of that business), and that if anyone is being obnoxious at or about trans people in those threads then either they're doing it in ways I'm failing to see or else it's being cleaned up effectively enough that it's gone by the time I look.
It seems your experience is very different. Where should I be looking for some examples?