Being brutally honest, in this very competitive environment, most candidates need to win their nom slate in order to receive an appointment. Not all by any means but most. If your DS is deferred and someone else on the slate is already qualified, your DS's odds will likely be longer. Thus, I would ensure alternate Plan A/Plan B is in place. If he has new SATs, significant new ECAs/awards, etc. or terrific 7th semester grades, I suggest submitting those. A rejection could lead to NAPS/Foundation, but it's not something I would count on.
Also, if he does have interest in other SAs, it sounds like the MOC is willing to give him a nom to one of those. It's not that other SAs are "easier" but different SAs sometimes view the same candidate differently. So, if USMA, USAFA or USMMA is of interest to him (and he's applied or could still apply), that's an option. Of course USCGA is always an option as no nom is required.