So the above scenario is a possibility, but then imagine the followup:
Feds to Zurich Canton: Tell swiss national X to update the warrant canary or ...
We have it spread out geographically for a reason.
Perhaps that's impractical, but I'm thinking about what would be needed to 'beat' the warrant canary system.
Legal "hacks" like this rarely work.
Not the most perfect example, but it goes to show what happens when someone unfamiliar with the law makes "logical" (to them) assumptions about loopholes that exist. That blog is a treasure trove of gems like the above.
If you have been ordered not to communicate X, and you communicate X, then you are in violation of whatever statute or court order was in place.
But you've probably looked at this and decided it is defensible.