Yes, but what about the rights of employees to defend themselves against carjackers in the company parking lot and on public roads after they leave work?
The employer can indeed be held liable for an unsafe work area to include the parking lots. If it can be proven that the area was unsafe or a reasonable person would have known the area to be unsafe and someone gets hurt, the employer can stand by. Letting employees carry weapons will not negate this liability.
If an employee wants to bring a weapon he can risk it and face termination if caught, or leave his weapon in his vehicle which would be park in an area that was not the employers property.
Rights are not absolute. You do not have the right to slander or libel or commit perjury regardless of the 1st amendment. You do not have the right to take a gun into my house or on my property regardless of the 2nd amendment.
It is still the owner’s property and he can decide who can or can not enter the premises and will be liable for reasonable or foreseeable hazards.