Oh I hear you. Guilty of a crime until proven innocent. Some cities specifically state it's illegal to fire a gun in the city "except" when it is defense of ones self or another. No one gets charged if it is in self defense because it is not illegal. They wrote it that way out of wisdom. To take the ambiguity out of it.
In this instance it did not become legal the next day just because the DA declared it so. The DA made his declaration that it was a legal action because it was legal from the very first moment.

It is no different than if it occurred in an unincorporated area of the county.

The officer more than likely was responding to a 911 call of people being attacked by a dog not of shots fired. Read carefully the dog was looking for his 5th victim. He was sent to serve and protect. To stop a dog attack. There is no snark intended in that expression. Someone else took care of the dog issue. Thankfully the City of Roanoke has quickly returned the gun and everything is back to normal. I'm all done. Thanks for listening.