[Permik]

Assuming US, I think that the gov't can't actually compel speech from an entity e.g. force to keep signing the canary. Warrant canaries are the way entities can circumvent the narrow case where the gov't actually can restrict your free speech, by creating a case where your lack of speak is telling. By this framework we can then come around again to the first point.

[bombcar]

The trick is they can just take over maintaining the canary themselves after black-bagging you.

But in general the idea works - in theory.

[gary_0]

The point of a canary is that it's cryptographically signed, and it's possible to set up a duress passphrase that will delete the key when entered, so if everything works correctly an unauthorized party can't keep posting signed canaries.