The EFF doesn't suggest actually using the warranty canary without court approval:
> What should an ISP do if the warrant canary is triggered?
> If an ISP with a warrant canary receives gagged legal process, it should obtain legal counsel and go to a court for a determination that it cannot be required to publish false information. While some ISPs may be tempted to engage in civil disobedience, EFF believes that it is better to present the issue to a court, to help establish a precedent. If you run an ISP with a warrant canary and receive gagged legal process, contact info@eff.org if you would like help finding counsel.
> What should an ISP do if the warrant canary is triggered?
> If an ISP with a warrant canary receives gagged legal process, it should obtain legal counsel and go to a court for a determination that it cannot be required to publish false information. While some ISPs may be tempted to engage in civil disobedience, EFF believes that it is better to present the issue to a court, to help establish a precedent. If you run an ISP with a warrant canary and receive gagged legal process, contact info@eff.org if you would like help finding counsel.