I prefer the comic book myself, which makes far more sense than what you just outlined:
where humans travel back to kill Robocop, because he is the initial terminator design (making OCP a Skynet allie, OCP is afterall the villain of the robocop property... it shouldn't be twisted into a good guy vs. Skynet, OCP should build skynet, or a part of it atleast). Terminators therefore go back to protect Robocop, as he is their ancestor. Crap hits the fan, Robocop learns the truth about what is going on. Robocop turns on the terminators.
but again, that being said, this isn't really good material for a movie... unless it was a sequel in a reinvigorated franchise/ or a new franchise. Also depends on who owns what property, at what time.