OK, that's fine in principle. I can understand why an employer doesn't want guns inside his buildings, but what about in the corporate parking lot? What happens to employees who are disarmed by their employer and then carjacked in the parking lot?
Furthermore, there is a HUGE issue here of what happens to diarmed employees after they leave work and are off company property on public roads and now they are disarmed and cannot defend themselves againt carjackers. When you take guns out of someone's vehicle, the impact of that action extends far beyond your property lines when that person leaves your property in his vehicle. You're disarming that person on his ride home too, which could be through a dangerous area.
This is a thorny legal issue, but I support the rights of vehicle owners. The restrictions will not make people safer at work because the criminal or the crazy person will not follow them anyway, and that's the person who is going to commit a violent crime.
Which is precisely why I have chosen to break company firearm rules when I have worked for companies that tell me that I cannot be armed. I'd rather be alive and unemployed than comply with company rules and be dead. Either that or never go to work there in the first place.
I even carried when working for Domino's Pizza. I had a .45/.410 derringer in my hand, under the pizza bag, when I went into the more dangerous apartment buildings. My boss knew it, too. She said that the company would not stand by me if I ever had to use it, but that she understood why I carried it.