""War" is one of those terms that is often abused. I hope we're not at war, because, as the saying goes, the first casualty is truth. And "war" becomes an opportunity to force on the populace unpleasant things that the government deems important or at least useful. And often those things hang around long after the "war" is over.
But it's incumbent on the Police especially to behave lawfully. They should know what their powers are, and shouldn't order surfers (or anyone else) around unless they're legally empowered to do it. Otherwise they'll lose the confidence of the populace. If there is a need for the Police to order surfers out of the sea, let the appropriate governmental process (I don't know what's required to create a law under the a National State of Emergency) happen.