Explain the purpose of including Meir Katz at this point in the memoir?

When Meir Katz appears in Chapter Seven, he is healthier than the other prisoners because as the gardener at Buna, he had received somewhat different treatment. As a result he was better fed.... healthier than the other and strong enough to save Elie's life. Ironically, after only a few days on the train, Katz too becomes a broken man.