Is "nasty tone" really the basis of silently banning people? Just because something offends a moderator, then all of their subsequent comments are censored?
Being offended shouldn't offer anyone any special rights. If something "offends" you, ignore it and move on.
I don't know of another forum where reasonably long standing members are banned silently, without even the courtesy of telling them. It's kinda a douche move.
Silent banning is more like censorship than banning - you're silencing someone because you don't agree with them, without telling them they're being silenced.
It's also a matter of where the line is drawn. Most forums ban obvious spam - viagra, porn, etc. But HN (IMHO) bans people for being overly critical, for not agreeing with the groupthink, or perhaps not having enough tact or politeness.
Silent banning has 0 effect on spam and trolls - they'll verify their spam/troll comment has appeared, and if it hasn't, just create a new account. The people it hurts are simply people who happen to offend a moderator.
You can be pretty confident not to post spam, but how do you know if your comment may offend some moderator? - These days most things offend someone. That IMHO makes for a 'walking on eggshells' type of forum, rather than an open place to discuss.
The far more damaging part of HN IMHO is the silent banning. It's a very ugly sledgehammer which is routinely used to censor dissenting voices. Victims of it have no real recourse even if they do notice they've been censored. It doesn't make for an open relaxed environment where people can express their opinion.
It's a lame, lazy and flawed system of moderation which ends up with a ton of false positives.
I wouldn't be surprised if this comment gets me silent banned!
For example, sending "offensive" tweets should not be illegal IMHO.