He WOULD be a retard. You couldn't sit einstein down in a thirty year old clone body and expect him to be a genius because he wouldn't have ever used THAT mind to apply anything, nor would he remember experiences his original body had.
He'd be a blank slate, a computer completely clean of software.
Just because a body and a clone body are genetically the same doesn't mean the clone body gets the other ones memories. That isn't how it works. They could teach Hicks things, but he'd basically be a kindergartner or a first grader in a thirty year olds body.
Its a bad idea, one that even in movieland, makes no sense.