What is a Warrant Canary of Trust.Zone VPN?

Do you know about Trust.Zone's Warrant Canary? You can find it here

A warrant canary is a method by which a Trust.Zone VPN services aims to inform its users that the Trust.Zone has not been served with a secret government subpoena.

Although Trust.Zone VPN is subject to Seychelles law and not subject to laws such as Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act of 2001 (the US Patriot Act), in the interests of transparency and accountability, we will be issuing a daily "warrant canary". This will protect Trust.Zone customers in the event we are required by law to be silent about any searches, seizures of data or requirements to log any actions of our customers.

This is a document put out and updated by Trust.Zone certifying that we have not been contacted by government agencies or coerced to compromise our user's data.  If such an event occurred forcing us to compromise our principles, we stop updating the canary.

In addition to a digital signature, warrant canary provides recent news headlines as proof that the warrant canary was recently posted. If warrant canary fails to be updated during the specified time then the user is to assume that the Trust.Zone has received a subpoena and should stop using the service.

Is it legal to publish a warrant canary? 

There is no law that prohibits a service provider from reporting all the legal processes that it has not received.