When you plan on wronging someone, you study previous mistakes of those who tried something similar, so as not to make the same mistakes?
Or, it has become a national security issue to control rhetoric coming from Iran, in particular regarding anti-semitism and denial of the holocaust. A piece of primary source literature that acts as a confession of guilt of someone from 75 years ago would do a good job of that. DHS/ICE is involved because it would have been a Customs issue to import it (meh, I'd call is war spoils for the prosecutor actually), and/or because it's a "Homeland Security" issue due to its possible relevance to US-Iranian relations.