People without a security background always look at things the wrong way. I do have a background in security at a maximum security facility I worked at a few years ago. Here's what a bubble gun looks like to me. It is a reservoir for liquid or other substance. That substance in the reservoir can be the bubble mixture but it also can be anything else, including explosive material. In other words, any substance that can be put into there. It just a reservoir looking like a gun. The substance in there could makes it a bomb actually. Security people care less about the gun function as the reservoir potential.
Other toy guns can also be modified in many ways to make them lethal. We once discovered a gun hidden in a kid's toy gun in an attempt to get it by us. Not the brightest attempt in our setting but potentially a better ruse at Disney.
Now given that all the three parks, not just Disney, rolled these out on the same day suggests that there was/is some threat that we will likely not be privy to. They best way to handle the various possibilities of toy guns being modified is to not allow them in and not sell them at all. You don't want someone to go into the park, buy a toy, take it out, modify it in some way to make it lethal and then bring it back in. Think outside the box folks, that's what security people do.
