At some point, no matter what HN does, being comfortable with its moderation requires you to take Dan's word for things. I take his word for it on shadowbans.
Ironically, I'm irritated with moderation in the other direction: ten years of "if you keep breaking the guidelines under alternate accounts, we'll ban your real account" sort of makes my blood boil (people having long-running alts does that too), but I roll with it, because I couldn't do the job better than Dan and Tom do.
This has gaps, as you know, and doesn't wash. Let someone turn a new leaf. Amnesty puts a stop to this.
I wrote a fun solution one time where the document comes with a token that needs to mature for a duration depending on the user. Then, when your [say] 30 seconds are expired the input area is displayed but the submit button only appears if you input enough characters - where enough again depends on the user. If you are likely to make low effort postings I want at least 500 or 1000 characters worth of low effort. In even worse cases ill also hold the comment for moderation - until I get to it. (which might be a long time)