Question
Legion and Skynet are two separate AIs, so while I understand that the 101 that killed John Connor no longer had to obey it's mission after Skynet was erased from future existence, I don't see how one of Skynet's products could have any info on Legion's plans.
Answer
I can't find the exact quote, but the T-800 mentions that it can detect "temporal displacements" which let him calculate the exact time and location a Terminator would appear. Then Sarah interrupts him and says "That explains the 'how' but not the 'why'." That's pretty much all the movie does to explain it.
Answered By - DeeV
