Based on Weaver term's comment about John Henry's importance in helping John Connor beat Skynet, it appears that John Henry also deserves protection. And, along with that, it is important that the Third Faction and the Resistance are joined in the future to fight Skynet on a coordinated basis.
Maybe because its he who reprograms the terminators so Bob and Cam can save John in the past.
John Connor's life is important because he is supposed to be able to defeat Skynet. That's why Skynet wanted to kill Sarah and young John. But keeping John alive is definiitely less important than defeating Skynet and preventing Judgment Day, i.e., John could be reasonably sacrificed if it would help attain those goals.
Thus, Cameron's mission is logically threefold. First, defeat Skynet however possible. She helped destroy the precursor to the Skynet of her future when she jumped Sarah forward in the bank vault and put her in a position to destroy the first Turk. Second, help the Third Faction and the Resistance join together. She did this by offering her chip to John Henry, providing him a way to escape the Zeira basement, where he was being targeted by the Kaliba AI, another Skynet precursor. Third, protect John Connor, which she did many times, beginning with saving him from Cromartie in the pilot.
These are straight-forward and obvious. It is not necessary to get into complicated theories based on conjecture and subjective interpretations. While those are possible because they haven't been explicitly excluded, they are essentially fanciful in nature, for the entertainment of jaded and bored imaginations.
In an imaginary world there is nothing tangible of course especially if its an unfinished story. But I rather want to find the coolest and most imaginitive ways to finish a story for myself or answer open questions and I think the Cameron took over the resistance version is way cooler than the simple, obvious version. Besides writers would do it too even retcon stories if that makes a story better.
I am not sure of cause but in some moments of the T salvation movie it seems like that T2 and T3 has not happened, because well just somekind middle man, I mean yes he was young in the end of T3 but he was after all the one who answered the call from the different places. as the person in Crystal Peak
I always pretend Salvation doesn't exist