I certainly wasn't suggesting he carries a loaded gun. I was using the juxtaposition to illustrate that weapon laws can be convoluted and somewhat nonsensical. Regardless, you're still held to the law.
Lots of people get into a LOT of trouble by possessing what are to them basically novelty items (maces, blackjacks, brass knuckles, lipstick knives, sword canes, etc.), without realizing the legal consequences. In many areas of the US, even possessing these items is a penitentiary offense. Carrying them in public is an additional crime. It adds up fast.
Add to that the fact that he's going to cary it in a vehicle, which has a much lower expectation of privacy than pretty much any other property a person owns and can be searched without a warrant, and the likelihood of said novelty item being discovered by law enforcement goes way, way up.
A tire iron or jack handle or other tool which has a nexus with the vehicle it's carried in can be used as a weapon, but they are primarily something else, and until you use it as a weapon it's not considered one. That's a lot different than carrying a club and trying to justify it as a tire thumper or some other tool, especially if the vehicle it's in doesn't have duel tires...
Law enforcement officers know weapons when they see them, and they know bullshit when they hear it. They also don't need to meet the standard of "beyond a reasonable doubt" to make an arrest, they only need "reasonable suspicion". In other words, a savvy law enforcement officer will gladly make an arrest for a weapon offense that he/she knows is unlikely to be successfully prosecuted, because it gets the weapon off the street and it creates a record of the owner for future reference.
And if he doesn't want a legal warning, he's free to ignore it.