IRL, if you took a tazer off a cop and shot them with it - you could expect to get shot with real bullets. Do this in a airport, even more so. Do it in a research base with nuclear, biological, and chemical weapons on it that's a known target of terrorists, and well...you see where I'm going.
This is also simply solved by not attacking the person armed with a lethal weapon. If you attack a dude wielding a shotgun, you should expect to get shotgunned. Or lasered. Or whatever.
This is also all acting under the assumption that people getting killed is a bad thing that we should try to avoid. The risk of death when you mess with sec heightens tensions and adds to the adrenaline of the game. People getting murdered in violent conflicts with sec is a good thing.