 Why is Rikud oddly satisfied about Crifer's limp foot?
Rikud knew that something which he could not explain had entered the elder man's head for a moment, but it had departed almost before Chuls knew of its existence. Under the tube at Rikud's left lay Crifer. Rikud was guiltily glad when he saw Crifer limp. Now Crifer said, "I've been reading again, Rikud." For a whole week that view did not change, and Rikud had come to accept it as fact. If he, Rikud, walked from one part of the world to another, it was with a purpose—to eat, or to sleep, or perhaps to bathe in the health-rays.
 It's evidence that imperfections still exist, and validates Rikud's feelings.
 It's new and interesting. Rikud is tired of the regular.  It means that people can hurt, which Rikud has an interest in.  He dislikes Crifer, and enjoys the fact that he is stuck with an anomaly.  It's evidence that imperfections still exist, and validates Rikud's feelings.