Airgapped is not enough, it should stay airgapped forever until erased.
I should have been more clear.: When I use the word airgapped, without exception I mean permanently airgapped. A computer without an internet connection temporarily is not airgapped.
A safe usually digital copy is not an easy task.
I wouldn't make a digital copy. I'd simply copy the private key to a second piece of paper in case something happens to the original.
Wouldn't burn it or give to the police. Give it to some poor people? I have a number of charities that I know could use the coin better than I would.
I would do nothing. As suchmoon says, the real owner might try to move the coins at any point between now and decades in to the future. You cannot assume the coins are lost just because that paper wallet goes unclaimed.