As far as I'm aware you -HAVE- to put all of your grades on; if you didn't, I would've dropped 2 D's I picked up from courses I knew I was leaving :c
If the predicted are out of reach he runs the risk of not getting in full-stop. On the other hand, if he's not far off he might get in on clearing regardless, presuming they don't check and drop the banhammer on him.
It's not -supposed- to happen, because you do have to declare anything that isn't a U.
If they were to check the results and find he'd tactically chosen to leave them off, he may even run the risk of having ALL of his University choices being made aware that he's technically lied on his application.