They simply argue that hate speakers should not be given as much time as their targets/potential victims/people not advocating hate, and their post is virtually white.
And none of the people who downvoted put their name to it by making an argument/reply/rebuttal.
In all seriousness though, HN has an echo chamber, it's the inverse of Reddit. Reddit and HN function very similarly with their voting systems, and everyone knows Reddit is an extreme-left shithole, but HN is getting more conservative, I've definitely seen a lot more comments that are low-effort and look like they could be from T_D now that Reddit is banning a fuck-ton of them for brigading. Give it a few years and I guarantee this becomes T_Dv2 (or at least a lot more like /pol/).
Seems like I have at least one such user following me around now, downvoting my comments (my anti-racist comments anyway) in different threads.
We'll see if they anonymously announce themselves with this post too.
Edit: And right on cue, the test produces a result: mere minutes after making this post - two more downvotes, including a post already downvoted.
So either someone is keeping themselves awake 24/7 to religiously reload a dead thread, or my comments page, using multiple accounts to downvote (which while completely insane is still flattering), or it's a bot with no limit (for reasons that can only be guessed at) that checks for new posts and downvotes automatically.
(Perhaps more tests are needed, I can then write a Medium and submit the results here.)
Either way it's an interestingly hostile response to someone commenting about far-right/racist users at Hackernews.
Some people are so childish.