MobBoss
Off-Topic Overlord
Why would you even approach a kid that you don't know armed with a gun if he's not breaking into a house or something?
The question is literally moot since this is not unlawful. Z doing this simply isn't against the law.
An armed guy in a car following me for no apparent reason? That sounds like it constitutes a pretty big threat to my safety. At the least, it constitutes stalking.
If he's in the car how do you know he is armed?

And no, i'm pretty sure it wouldn't meet the legal definition of the charge of stalking. Again, following someone in your car is not against the law, and you sure aren't allowed to attack someone simply because of it occurring.