It is a shame that nobody understand the plot.
They didn't send Gracie without a plan, at the last scene she said about the core "It was the plan from the beginning", she was sent with goal that she is going to sacrifice herself and eliminate the terminator. But guess what the difference between sending a robot and a human that she is a human !!, she was afraid for her life . Sarah Connor bait is the true plan that needed to be done!, But Gracie went scared and wanted to be buried as deep as possible in the ground and just keep hiding. Sarah Connor get used to it that the terminators that helping them is weaker than the one sent to kill them, so she tried to find solutions like the weapons with the electro-magnetic pulse, which gave Gracie some hope, but that plan did not work out. In the end, she saw that Danny wasn't cooperating, doesnt want hide, the leading woman who rescued her came out and said "we stay here and fight", she showed the courage of a real warrior who stopped running, only then Gracie understood why she was the one sent here and did her job not from a direct command but out of emotion and willingness (as Arnold said, because I choose to do it). And about Ligion? it means that no matter what you will do everything is repetitive.And the first scene show that you cant prevent this and just end it. it is a constant struggle.
Brilliant script that everybody missed