It's the moral issue at work.
I think the point is that it is an "us against them" (humans vs machines) bottom line.
So--- Arnie2 may have been reprogrammed (as has been mentioned already) to obtain the necessary clothes, weapons and a vehicle to begin his mission
but not to kill anyone in the process. This is why everyone at the bar survived.
Young John reinforces this with the "You can't kill anyone" order.
The point being that if the Terminator were allowed to randomly kill at will- it reduces the humans controlling the Terminator to the same level of the machines themselves- being cold and calculating.
Why did he try to shoot the black guy? Well John initially ordered the Terminator to grab the long haired jock for calling him a name
rolleyes). The black guy "attacked" the Terminator, so I assume it went into self defense mode and planned to "terminate the threat".
Now the point of the "***** you were going to kill that guy!" scene was a set up so the movie doesn't become a cute "Me and My Terminator" buddy film. John finds out very quickly that The Terminator isn't a toy to mess around with. And John does some growing up within a few seconds going from "This is the coolest thing EVAR!" to "Holy ****! I'd better not screw around- this thing is dangerous!"
One of the themes of T2 is "life is precious". That was the point behind John freaking out when Sarah sets off to kill Dyson, and the Terminator agreeing that killing Dyson may prevent the war.
Sarah has her own breakdown when she realizes she nearly became what they are attempting to stop- she nearly killed a man in an effecient terminator-like fashion and would have committed murder in the name of "changing the future".
That is what the machines have been doing all along. We're supposed to be better than that. Otherwise instead of sending a Terminator back to protect John, why not just send it back to kill the guy who invented Skynet? Fight fire with fire? No because all human life is precious. And it takes a great deal more intelligence to "figure a way out of this mess" without simply resorting to "superior firepower."
But I suppose the movie would have been better if the "good guy" killed dozens of cops who were just doing their job? Really?
They probably spent the rest of their lives in wheelchairs after getting kneecapped. Good enough?
Kevin
