Following, perhaps, but not blocking.

One of the nice things that HN affords is that it doesn't really support filter bubbles--at least until mods or the community downvotes you to oblivion. Thus, there's a good chance that people at least get exposed to ideas they might otherwise ignore.

Hell, I can think of several posts where I've strongly disagreed with somebody else, only to be in jovial agreement or discussion a few days later. I'm not sure that a blocking mechanism is really needed; if people are being deliberate and abusive trolls, we have ways of dealing with that, right?