I don't know if you missed it in the article or simply didn't read it.

The case being discussed is one in which a family moved from BC to AB. As a result, they were able to leave behind an open investigation into child abuse.

There is no formal process of warning (alerting) other jurisdictions, so they got to start with a clean slate in AB.

The judge thinks that having these warnings cross boundaries might save lives.

So literally nothing to do with the emergency alert system.