I'd expect more than a single off-color comment before banning someone. This particular user has a long set of perfectly valid and relevant comments throughout his comment history. There should be a pervasive problem with the user that fails to be resolved, even after an open dialog with others, before the community resorts to the boot. Even then, there's no reason for a hell ban specifically. Hell bans are meant to throw off unmonitored spammers who aren't meticulous enough to check that they do in fact have clean accounts to spam through. The Jesus-Spam that's been making the rounds recently is a good example; lots of Bible verses and more or less the exact same message in every post, not at all relevant to the link. Obvious spam. Sabat obviously isn't in this category.
However, the moderation system on HN isn't even opaque; it's a pitch black box. Zero accountability.
What you refer to as "Jesus-Spam" is the tragic rambling (and randomly generated "messages from God") of a talented software developer with schizophrenia.
Usually I've seen a paragraph or two of related and often insightful commentary, interspersed with randomly selected biblical verses or Markov chains (the "God says" sections).
I've known two people that have been hell banned here for single one-off comments. In both cases it had to do with supposedly disrespecting prominent Silicon Valley big shots that are worshiped on HN (eg in one case it was about Chris Dixon).
In my opinion the fastest way to get banned from HN, is to say anything negative about the elites. Even if you're just criticizing, that'll be enough to do it.
However, the moderation system on HN isn't even opaque; it's a pitch black box. Zero accountability.