I don't doubt that you've seen examples of that, but I've seen plenty that go the other way. Heavily downvoted comments that are only slightly defensive of him, and others that rise to the top for bashing him when it isn't even relevant to the conversation. It really depends on the thread. Different topics attract different crowds.

I saw a lot of downvotes and defenses like you say, but the down votes, as far as I have seen, were on rants or reddit type blurbs about Trump which people do not like here. And the defenses were well thought out. Anyway that is what I have seen; i started checking because I thought it weird there are so many Trump supporters on here (might still be the case: as eu person I also find it strange there are a fair amount religious people on here; I do not mind, I am just curious to things I do not expect to find).

The average vocal HN commenter on these matters are much more likely to be a fairly conservative techno-republican than elsewhere on the internet e.g. nearly every thread I've seen on the Capitol Riots (apart from the main one, which after being flagged and restored had an influx of fresh blood) has some kind of smarmy "ah yes but what about the (black people) looting and murdering in the summer". Similarly any thread on gun control shows just how much some Americans view gun violence as a mere cost of doing business so they can own an assault rifle.