There are 7 bus stops at CBR, one at each village, plus one at Old Port Royale (food court, main pool, gift shops). NO ONE, repeat, NO ONE has a room that's far from a bus stop. Let's say he wants to go to Magic Kingdom. The Magic Kingdom bus makes a circuit around to EACH bus stop before it goes to Magic Kingdom. He'll never have to take a bus to get to a bus! Now, if his room is kinda far from Old Port Royale, say in Trinidad South, he has the option of catching an internal shuttle to get to Old Port Royale. The internal shuttle is just another Disney Transport bus, no smaller, no bigger, and it's not a tram or anything like that. But CBR is lovely to walk around in.
It also seems surprising that he KNOWS that he'll be staying in a buidling far from Old Port Royale. Rooms aren't actually assigned until a few days prior to arrival. More likely, all he knows is that he's not staying in the 6 buildings closest to OPR, since they cost more and are reserved rather than requested (it's called "preferred location").
If he's young and not injured or ill, he won't have any problem walking around CBR from any spot to any other spot. Does he go to college? I had further walks on campus between classes (at Dinosaur University, GO FOSSILS!

) than the distance from Trinidad South to OPR.
I'm sure he'll love CBR and WDW!