Would you prefer he shot it? He'd be within his rights. I've shot squirrels that lived in my attic. I think it's perfectly justified if they are damaging your property.
Since deer are a game animal, I'd assume the DNR in your state would have looked down upon killing of a deer outside of season by someone without a permit.
And yes, I understand urban deer can be a nuisance. There are better ways to deal with the situation than beating and/or killing them.