Considering the nature of the script idea itself, sending projectiles at people as a defense against possible future attack sounds an awful lot like nuking your neighbor for looking out the window at you, just in case he was about to jump out and shoot you.
Perhaps it is an aggressive nature, coupled with fear of the aggression of others, that is behind the thinking, but in an environment other than a combat zone, it's just downright antisocial.
And IN a combat zone, you'd probably get kicked out for using something not part of their sealed, anti-cheating system.
Please understand, not everything people say that you don't like is a potential threat, and people not helping you with a weapon that targets people who aren't shooting you is to be applauded, not condemned, if you have any real feelings whatsoever.
So basically, someone comes to SL, gets frustrated, and wants to lash out. Gee, everyone's been there. Not everyone shoots people out of nowhere for it, though. Sure, effortlessly dealing with those who would do us harm is an attractive idea, but implementing it isn't so simple as shooting people for looking at you funny.
Also, even things like, "let him get banned" are just symptoms of the same problem. Letting someone cause problems in the hopes it will remove them is just as bad as actively causing problems oneself.
I'd never wish to see anyone pushed out of the community for seeing things differently; better to maybe try to get people to see that "other differents" can make sense first.
Personally, when in a situation where objects might be flying at me and either disrupting my fun, or taking points off of my combat meter, I prefer small, floating, angled deflector shields. If the shield rezzes at an angle to the oncoming projectile, it can deflect the projectile away from you, rather than being pierced by it.
Incidentally, this also works great in dealing with anything thrown at you by, say, an automated attack script that targets you whether you're an aggressor towards anyone or not.