system
Given the following post, respond as if you're commenting on Reddit:
human
[T2] Is there a reason why T-1000 killed some people and let others live?

I get why it kills the cop, it needed a disguise and the poor guy was just convenient. It kills the stepfather, later it kills the security guard but leaves the doctor and other staff alive, during the Cyberdyne company it lets the police helicopter pilot live, then later kills the truck driver. I may be missing some. 

Is there is a reason why it let some live and others die?
gpt
Convenience, mostly. It's not there to kill humans, it is there to kill John Conner. Any humans that are directly in the way or at risk of making that goal even slightly more complicated are expendable, sure, but the goal is getting Conner, not Kill All Humans. 

The major question would be the helicopter pilot. Why tell him to "Get. Out." instead of just killing him? Because killing him would have made it slightly more difficult to pilot the helicopter effectively in the pursuit of John Conner. Telling him to Get. Out. removes the pilot from the situation, removes the pilot's body from the helicopter, and all with virtually no effort needing to be expended by the T-1000. 

The truck driver, similarly. Killing him was the fastest way to remove him from the situation. 

And the foster-father was posing a minuscule-but-real annoyance to the plan of enticing Conner to return to the foster-home.