BS. First of all, WD 40 isn't a rust preventative, it's a penetrant. Secondly, if you soak ammo in WD 40, it's going to kill the primers. It eats through the sealant used by the military on the primers. Model airplane glue dissolves in WD 40. My Father in law is an RC airplane buff and has shown me some cool tidbits of info on those.
Now, about unsafe at home vs on the street. You don't know what you are talking about. He may have children at home, or his living situation may be such that a loaded gun at home is more of a liability than anything. Get a clue, you don't know anything.
Mike