Is Kraus committing a sin?

Chapter 14: Kraus
Diligence and industry are qualities that people all over the world hold very valuable. We set honest, hard workers as role models and representatives of people with good morality. It is actually true that these kinds of people benefit the world these days with people increasingly turning deceitful and self-centered. However, does this still apply in the case of Kraus, and all other prisoners in the concentration camps, for that matter?
Kraus worked very hard and restlessly like a laborer does. “He works too much and too vigorously: he has not yet learnt our underground art of economizing on everything… He does not yet know that it is better to be beaten, because one does not normally die of blows, but one does of exhaustion… oh no, poor Kraus, his is not reasoning, it is only the stupid honesty of a small employee.” Primo Levi says that in the camps, exhaustion is more dangerous that the blows one receives from the Kapos and SS soldiers from being insolent. So is it right for a man to be lazy in the concentration camps, while the morals of the outside world regard diligence as one of the greatest values of a person? Is it a sin to be lazy when one would die when worked too hard? Another contradiction between the situation in the concentration camps and the outside world is presented in this chapter.
I heard once that it is a sin to kill oneself, that one should strive to survive as much as possible. According to this statement, one should therefore be lazy in the camps in order to survive, rather than be assiduous and increase the chance of dying. If being insolent, along with committing suicide, is yet another sin, I believe that the latter is a greater sin. Survival is ultimately more important than diligence. This is, however, only an opinion of mine, and others may have different claims to what is right.