I agree that it's not that simple.
Responsibility cannot be confused be with ruthlessness, barbarism and brutality. Jews had been living peacefully and lawfully, and the conduct exhibited by Nazis was far from being responsible, i.e rational. Nazi guard's definition about Jews being subhuman was not based on rationality or rationale. His definition (Jews being subhuman) was based on unrealistic assessment, which was not based on rational thinking or rationale
If, in self defence, a woman kills a rapist who is bent on raping her and even killing her in the process, should she be called irrational? I don't think so. She has every right to defend herself. Although she didn't want to kill that person, she was forced to do it.
In both cases, one person (Nazi guard) is unrealistic while the other (woman) is realistic, although both of them eliminated a human.