Ramsets use .22 blanks, not bullets, and would have the same issues being used as a pistol at range as any other powered hammer. Even if you override the safety, and either modify or practice with it enough to be reasonably accurate, you’re just not going to do much damage if you’re more than an arm’s length or two away.
Nails have terrible ballistic performance, and there’s nothing in a nailer meant to keep the nail going straight for more than 10cm or so. A nail launched into air (rather than a hard surface) from a nailer would start to tumble almost immediately.
You’d literally be more effective throwing the nailer at an attacker than trying to shoot them with it.
I took the time to watch some videos of people testing this.
Aside from all that, we’re talking about a tool designed to push a fastener into material while in contact with said material. A gun is a tool designed to push a bullet into a target at a distance with some level of designed-in accuracy. These are not the same thing. A power nailer can certainly be used as a gun, but it can also be used as a step stool, a ruler, or a door stop. Usage outside intended purpose doesn’t change the nature of an object.
Hey, if you want to call your PA nailer a nail gun, that’s fine. There’s no law requiring accuracy in speech, and of the entire power hammer category a PA nailer is probably closest.