"Yes but melting it down will also keep the plant out of skynet's hands. Wouldn't that do harm to skynet also. "

"Wow, where to begin.

1) I get the impression that John doesn't hold all the cards in the future and that there are those (subordinates) who oppose his use of reprogrammed Terminators. This is what Cameron was referring to, that people won't like the fact that John Connor is willing to risk his life to save a machine. Perhaps this is something Cameron has seen first-hand, possibly when he saved her from Skynet. Then again, she could've just been referring to herself, that she is upset by the idea of him putting himself in danger for her sake.

2) Maybe the war isn't going in the Resistance's favour. Remember that time is in a constant state of flux and that anything can change at any time. Maybe the Resistance was attacked or they attacked a Skynet facility, who knows. There are rumours that there are dozens of different factions in the future, other than the Resistance and Skynet.

3) I remember Dekker stating once that when John decided to re-activate Cameron he actually took her side, the side of a machine, in favour of his mother's side, the side of humanity. His choice of siding with Cameron (machine) as opposed to siding with Sarah (human) is apparently a problem he'll face in the future, and Cameron is afraid that he'll make the wrong choice."

"it also makes me wonder if the long talk he had with sarah may have pushed him over the edge (they had a lot to talk about, which made for a great scene there). i know that one of the common themes of the show is just about every guy sarah gets close to she ends up losing, but the ongoing cancer scare is getting depressing."