If it was me I'd argue that even the Nazi found the concentration camp horrifying.
True believers? No. Remember, too, that the camp system got its start well before they began racial purification, as a way to isolate and indoctrinate members of their society. Likewise, the death camps were a way to avoid the psychological effects of participating in mass shootings that they ran in to earlier. As far as most of Germany was concerned, the death camps were something along the lines of, "We know enough to know that we don't want to know." (Though again this doesn't really account for things like the mass flood of letters and pictures sent home by soldiers about killing POWs and various undesirables.)
Admittedly, it's a nice little trap for the ones clever enough to suspect the "obvious" answer of 'no' is a trap but not clever enough to read the class materials or pay attention.
A trap?
The obvious answer to, "Is it morally acceptable to stop Nazis from committing genocide?" is yes. A student who has something between their skull will think that that is too obvious if it's left to their common sense; ergo, a clever student who has not payed attention to the class will answer "yes" because it's the opposite of the obvious answer, while one who has will answer "no" for the reason previously mentioned.
Though given that most moral relativists tend to be anthropologists and the like trying to excuse horrendous practices because they're part of a given culture, they'd probably answer "yes" because if you interfere with Nazis committing genocide, you also interfere with systematic child abuse, genital mutilation, &c.