You're confusing corporations with people. A corporation does NOT have the same Rights as an individual that owns property.
Keep in mind that the primary reason corporations were founded was to avoid individual responsibility. With Rights comes responsibitlies, and corporations want the best of both worlds. Screw them.
No reason the employees can't leave the weapon at home
Should they leave their Bibles at home also? Or any other items that some company bozo might find offensive. People have a Right to have whatever they like in their private vehicle.
Yes, if company policy bars all religious stuff in the office.