I am not entirely certain that Stanley is considered evil in the novel for a couple of reasons. The first would be that Stanley is oppressed under the heel of the South African government. The very fact that he has to operate underground and that his movements are covert would reflect that even if he is bad, he is nowhere near the government that forces him in such a condition. Stanley is also fighting for a just cause. This would have to cast him in a different light than pure evil. If the label of evil is sought, I think that Brink would suggest that it is with the South African government that engages in kidnapping, torturing, and killing of Black South Africans, and eventually White ones, who speak out against the Apartheid system. This would be more where the evil content lies than in anything else. Stanley might be a figure whose exact motives are unclear, but I don't think that Brink sees him on the same moral, political, and social level of culpability that he sees the South African government as. It is here where I think that Stanley can be viewed in different lights, but being "evil" would be more reserved for the forces that perpetuate the policy and enforce the practice of Apartheid.