Nostromo's second line of defense is that serving the rulers does provide material rewards for the People. The family has even been rewarded while he has not -- so in a sense he has passed Teresa's "supreme test" of selflessness.

Teresa seems oblivious to this reasoning, as well she might: it was only through Mrs Gould's personal intervention that the Viola house wasn't demolished by Sir John's railway, which Nostromo helped build.