Yeah, I figure he's working with Angela; mix precognition with technopathy & you've basically got Rebel.
Plus, Noah can't be Rebel since we know he's doing other stuff during the hacking, & Angela herself doesn't know computers well enough.
Spoiler Below It would also explain sending Hiro & Ando to protect Matt Jr.; Angela probably had a dream about the little guy being the savior or something.
And remember, "I'm-a Luigi, number one!"