James Cameron wrote Terminator so unless James Cameron says it’sa prequel, it’s not. Comic books do this shyt all the time and it’s not considered real. Spider-Man vs Superman, Batman vs Hulk. Those weird one shots aren’t canon. This is no different.
If Cameron doesn’t co-sign it, it isn’t. Just because rights were sold to make a comic out of it, then one of the multiple people who will write a story for it, rewrites the story to something else, doesn’t trump what was originally written.