I suspect this is really VERY BAD reporting.
The probation convict was carrying an object as a weapon.
It would be no different if he used his automobile as a weapon.
The law makes a distinction between using a car as a weapon and merely driving the car. The article does not indicate that he used the BB gun as a weapon. Besides, anything can be a weapon, a sharp stick, a rock, or a 2x4. You going prosecute people, even 2X felons, for having those?