It was used previously too, one of the nazi "princes" also called german a "divine language" so it wouldn't surprise me. Latin was more widely taught in the past as an academic language, and on top of that, wouldn't surprise me if the nazis had some entanglement in their ideological BS connected to latin. We are slowly finding out more about the side of the neanderthals, I hope the story gives us answers in some of the things the nazis have taught them as part of the cult they made to have control.