You can say some things anonymously, but I'm not sure how far does it extend. Anonymity is tested not by posting under an alias, but when somebody tries to break it. If you get into the middle of real controversy - how far would HN willing to go before they wipe your account and possibly give the details they have (IPs, email, etc.) to the law enforcement, from where they'd immediately be leaked to the press? Was this ever tested in practice - i.e. somebody anonymous on HN was attacked and kept their anonymity?
I'm not talking about a court-mandated warrant. I'm talking about a friendly chat with a fellow law enforcement person who cordially asks for help - who needs warrants between friends? And you do want to be friends with the law enforcement, because it's a bad enemy to have, aren't they?
> It is not their duty to ensure that you can say anything here.
I'm not saying it's their duty. I am saying you can't at the same time claim anonymity is alive and well and say nobody actually will protect your anonymity once push comes to shove. If that's the case, then anonymity essentially does not exist where it counts. Nobody cares that you can anonymously praise the Dear Leader. Anonymity is only important when somebody has real reasons to want to break it. It's like with free speech - nobody worries about speech that everybody likes being free. You only need free speech protections when somebody actually wants to censor, otherwise it's just vacuous.
Maybe yes, maybe not, but who cares if nobody ever finds out? And cops are pretty much immune from most illegal acts on the job, once they are sure they are doing the right thing, or can convincingly pretend they were, and once there's no law on the books explicitly, in minute details, prohibiting exactly this particular behavior. That's "qualified immunity". As for the other side, who's going to prosecute them if the law loves them? Private users, who probably can barely afford one hour of lawyer time?