He reinforces the theme when Sarah nearly kills Miles Dyson. She's methodical and cold and ready to kill him without a thought. It's when she realizes what she's doing - murdering an as-yet innocent man - that she pulls back in horror and needs to be comforted by her son.
Although as a side note, the first time I ever saw this movie was on TBS and I missed the first 30 minutes (and the first movie). I legitimately thought that John was lying about Kyle Reese's existence. I thought John Connor had been the one to travel back in time and save his mother and he'd simply given a pseudonym. I totally got these incest vibes from how overly concerned John seems about his mother.
"During the writing process, he was in his living room excitedly explaining the T-1000 to his friend and collaborator Stan Winston when Winston raised a concern. "I don't know who the bad guy is," Winston said. "I need a specific character, a specific image." To Winston, what Cameron was describing sounded like a blob of goo, not an iconic evildoer. "From a story standpoint, I thought it was a problem," Winston later recalled in an interview for the picture-book history of his story, "The Winston Effect." Cameron respected Winston's instincts for creating memorable characters, and he started reconsidering how he would shape this one. Later that same night, the effects artist got a phone call from his friend. "I've got it!" Cameron said. "He's a cop!" The form the T-1000 would take for most of the movie was a Los Angeles police officer. This solved the storytelling dilemma Winston had raised and also gave Cameron an opportunity to underline a central theme in both of the Terminator movies - how people, especially those in violent jobs, like soldiers and cops, can become barbarized. "The Terminator films are not really about the human race getting killed of by future machines. They're about us losing touch with our own humanity and becoming machines, which allows us to kill and brutalize each other," he says. "Cops think all non-cops as less than they are, stupid, weak, and evil. They dehumanize the people they are sworn to protect and desensitize themselves in order to do that job.""
Source: https://www.amazon.com/Futurist-Life-Films-James-Cameron-ebook/dp/B0034184U0