I don’t think most are afraid that people who know to search HN will cause any problems by searching it, rather that with increased public visibility will become popular amongst the types of trolls, scammers, spammers, political wackos, etc that inhabit (insert your least favorite social media or link aggregator site).

I have to admit I agree. I really like the benevolent dictatorship which does not allow that kind of BS, even from me. (The time dang gently reprimanded me for some kind of sarcastic attack, upon reflection, I decided that I liked this high standard, and resolved to do better.) I’d hate for it to change too.

Agreed, I've had a similar experience. So I'd be fine with limited public visibility, and I think my experience won't even change if google loses access. However if it's done with robots.txt, does tha tmean algolias crawler will also lose access? That would be a shame, but even then it might be worth it on balance.