They touched upon that in Judgement Day with Sarah going rogue to go after Dyson, as his research and programs would become Skynet. Dyson realized what he was doing after the T-800 cut open his arm (with coaching from humans of course), and even though he was already dying due to be shot by SWAT, he still stuck it through to ensure his work would be destroyed. The only thing this really lacks to what you're suggesting is that T-1000 was absent from the bulk of that encounter. If he had been present though, would John have just been his single target or would he have just been full melee on everyone, including Dyson? Can Terminators update mission protocols without transmission capabilities to home base (Skynet in the future)