I agree with most folks around here that this overzealous knee-jerk reaction to knives by much of the general public is ridiculous. No one should ever be fired just because of carrying a knife (it's how you use it, stupid!).
HOWEVER, one must not put 100% of the blame the company boss, manager, or supervisor for having an anti-knife ethic. Many of these people, if allowed to follow their own personal common sense, could care less whether or not an employee carried a knife or not. Many are worried about the LIABILITY the company or even themselves may have to shoulder should something happen. This liability issue is why companies and other entities have to get various forms of lawsuit insurance, retain consulting lawyers on staff, and institute so-called 'zero-tolerance' policies.
Lawyers (or more specifically, their lack of ethics) sue companies whenever, and whereever they can to fatten their own wallets, all the while ignoring the possible damage they may be doing to often honest companies. You could also blame the lazy-get-rich-quick mentality many people have these days. However, I still place most of the blame on the lawyers, for if they had any form moral standards, they wouldn't accept to take on all these frivolous lawsuits.
In the past I have worked in a profession that involved the government, companies, and lawyers and in the beginning thought that there could be such a thing as a lawyer with some redeeming values. However, from my own experience, unfortunately I have never encountered one who was not willing to manipulate, cheat, or out right lie to win a case regardless of who ended up getting hurt (or in some cases dying) to win cases.
While I'm sure there are some lawyers who read these forum who may disagree with what I am saying, this is my own personal opinion and I stand by them 100%. Next to the terrorists, I feel that lawyers are the biggest threat to honest businesses and the American dream. If you have thoughts about trying to sue me for slandering the law 'profession' you only prove my point further.
So basically if you were bored enough to read my pseudo-rant, many of these supposed anti-knife folks are just covering their asses from getting attacked with some frivolous lawsuit that may end up costing themselves and others their livelyhoods (and I can hardly blame them).