I just read the synopsis, I’m curious what age your son is or how old you were when you read it? I’m not sure my son is old enough for it.
Don’t let your kids read Roald Dahls adult literature either, Switch Bitch is no Giant Peach
Speaking from memory, I really appreciated being able to read books with relatively "mature" topics like that (isolation, survival, etc.)
If he can read chapter books at all, he's probably old enough.