I understand where you're going for, but imo that's never been a valid argument against self-determination.
I think your argument can be made simpler: why should we trust people to be allowed to decide for themselves? Won't they decide to do stupid and harmful things? Won't they decide to hurt eachother? Won't they decide to steal from eachother, and murder eachother?
No, is the answer, because laws were created somehow, right? We don't trust the government to babysit us - we created the government so we wouldn't have to babysit eachother.
We don't need the board to tell us what we can and can't do - we can figure that well enough on our own. What we don't need is a board that assumes it knows best. It doesn't, it can't possibly, in fact it is existentially unable to do anything but raise shareholder value. So, the more employee self-determination, the better.
I think it's very unlikely that employees will decide they want to have guns at work instead of, say, a security system, or maybe offices in places with low crime, etc. I think it's very unlikely that employees will decide, I dunno, that they want the right to shit on eachother's desk, or whatever other fairly-objectively-negative thing you can think up. The right to paste racial slurs all over the office, maybe? Bigotry, bullying, and hatred are swiftly becoming a minority, and a fair system almost universally causes those minority viewpoints to lose power. They only maintain it in imbalanced systems...
And worse case scenario, if Amazon turns into the kind of office where you have to shoot your way in just to get to your desk, we can have the government intervene and shut the place down (with our labor laws), and maybe someone can set up a better business where you don't have to shoot your way to your desk.