In my opinion, I don't think anyone needs a gun or pocketknife at Disney World. I don't care if you're a good guy, a bad guy, a citizen, or a cop, you don't need a gun or a pocketknife at Disney. Leave it at home or at the very least in your room. I have certainly found myself in situations in my life where I don't feel especially safe or protected and some sort of defense might have been a good idea just in case, but that has NEVER happened at WDW, and I've been frequently each year since the 90s. If you're still don't feel comfortable for some reason without your gun or knife, go somewhere else but don't break the rules in the name of "safety." In reality, you're more likely to be jeopardizing safety than enhancing it. I mean the urgency of setting up these metal detectors may have come from the man who got caught with his gun at WDW last week. Bottom line is when a place says no guns, it means no guns and that applies to everyone. Just as when they say "keep your hands, arms, and legs inside the vehicle", these rules apply to everyone. No exceptions.
As to them stopping toy gun sales, that seems to be more of a safety thing rather than anti-violence thing. Unfortunately, it's necessary in today's world, and while the internet always seems to supply us with an abundance of "experts" on "security theater," I think we all can agree that heaven forbid something were to happen without these metal detectors, people would be up in arms about Disney having too relaxed security procedures. Personally, I'll take the slight inconvenience if it means making the parks even slightly safer.