Thing is that the tv show, unlike the movies, don't seem to work in a closed loop. What this means is that John was never familiar with the Cameron Terminator design. We know this because of how Judgement Day had been pushed back. In the timeline from which future John is operating, there was no Cameron sent to the past, so he was never familiar with her model.

I could be wrong about this, but that's what I assume at the moment.