CB2001 said:
Well, if you think of it in that context of the films that are out, he WAS the catalyst for it becoming self aware. If John hadn't been born, Skynet never would have sent a Terminator back in time to kill his mother Sarah, he wouldn't have sent Reese to protect her, they wouldn't have lead it to the factory (in the deleted scenes, Sarah Connor actually planned on going to Cyberdyne and destroying the factory in hopes of stopping Skynet's existence with the help of Reese, hence the creation of the pipe bombs), the Terminator wouldn't have been crushed in the hydraulic press, the remains wouldn't have been found (in a deleted scene, you see two guys who work there find the crushed processor, and after Sarah is loaded up into the ambulance, it is revealed the factory is Cyberdyne Systems), Miles Dyson wouldn't have reversed engineered it, Skynet wouldn't have been created and it wouldn't have become self aware.
However, due to John being born, Skynet did send a Terminator back in time to kill his mother to stop him from being born, John sent Reese to make sure he protected his mother and conceive him, she and he lead the Terminator to Cyberdyne's factory, crushed it in the hydraulic press, the crushed processor was found by workers of Cyberdyne, Miles Dyson reversed engineered it to create the processor, which then lead to the creation of Skynet, and when it was turned on, it became self aware, caused Judgement Day, tried to wipe out all of humanity, John rose as a leader, and then the loop began again with Skynet sending a Terminator back in time to kill his mother.
Long story short, John is the catalyst for it becoming self aware because he's responsible for it's existence, much like how Skynet is the catalyst for his existence.