10. "but why not go back to the day before T1?" In response to In response to 9
Send the T-1000 liquid metal model to the same time they sent the first Terminator.
There's no way Sarah and John could survive the OG Terminator AND the T-1000.
And even if John sends back an OG Terminator reprogrammed to help them, it would be an even match for the "evil" T1 model, leaving Sarah and John to face the T-1000 alone...