I would offer my help recommending or picking out a gun, taking him the the range to help him learn to shoot, but I woudn't offer to loan him a gun. If you have one that you don't want you might offer to sell it to him, but I would more likely visit a gun store with him.
It sounds like he has reasons to be concerned about this safety and his property so he needs to take the initiatave to buy his own gun. If some one breaks into his car or house and steals something, you don't want it to be one of your guns.