Therefore, I still think the only real fix to the problem is tort reform. Take away the sword of liability hanging over the business owner's head, and much of the motivation for firearms bans will go out the window.
Right. If business owners were not held responsible for weapons carried by employees for personal protection or their use (versus employees who carry weapons as per their job descriptions), a huge amount of the problem would go away. The main issues would likely then become the regulation of the visibility of weapons carried for personal protection while one the job, how the weapons are secured or retained in the workplace, and whether or not the weapon would interfere in the performance of a job.