^ Those are interesting points. It could easily be attributed to filmmaker laziness, but if Sarah IS a cyborg that'd be a hilarious twist in the next movie.
Oh and not to mention that when they time travel to 2017 they get hit by a car going at least 50 MPH and it barely harms them, with Sarah taking the brunt of the impact.
I half expect the next Termy movie to reveal that every single person in the world was changed to a cyborg.