used to be able to redshirt, they closed that loophole.
if you REALLY don't want to start him that means you also can't play him, and you lose a yr of eligibility, but he'll practice and improve. Just leave him off the depth chart set at mop up and make sure you have at least 2 (preferably with an overlapping third) players at each position and as long as he doesn't play any minutes he doesn't seem to mind not starting. He only needs to start games he plays to be happy.