One can trade and warn the public simultaneously.

If you're worried about getting claim-jumped by an HFT firm subscribed to the public-warning system, a few millisecond delay might allow for trade execution?

Once you plan for any delay then the ethical/financial discussion then goes to why not 0.1s or 1 second or two? It might be more ethically balanced, and less of a PR nightmare if a hedge fund were satisfied with maybe matched parallel feed and the advantage they get for just having the infrastructure to respond to a richer signal sent at the same time as the public warning. The public warning is a yes or no to send, but the feed might have added data such as uncertainty, or initial locations.. etc.