I have to agree with you. Freeman of the land come to mind.
I think the danger here is the interpretation of the prohibition on telling people you've been served with a secret warrant.
Whilst you seemingly can't force someone to do something the fact that not doing that thing is effectively telling people you've been served a warrant is grounds at least to take you to court.
I can only imagine this canary process being manual, if it were automated I'm unsure it could be considered speech (obvs: IANAL).
I think you're taking non-US[0], non-lawyers speculating about US law a little bit too seriously. I mean it could be argued that we shouldn't even be commenting if we don't know, but where's the fun in that? It's Hacker News, not Lawyer News :)
I'm not comparing them, in that paragraph I'm commenting on the parents comment about people being slapped down by surly judges. That's why is in the first paragraph on its own.
I think the danger here is the interpretation of the prohibition on telling people you've been served with a secret warrant.
Whilst you seemingly can't force someone to do something the fact that not doing that thing is effectively telling people you've been served a warrant is grounds at least to take you to court.
I can only imagine this canary process being manual, if it were automated I'm unsure it could be considered speech (obvs: IANAL).
Until tested in court it's up in the area.