It is perfectly plausible that he didn't know. How much would a grunt like him be familiar with details of major operations? He certainly didn't have the need to know, and details of the extermination program were far above his pay grade.
Ex-FM Lieberman: Firebomb attack in Jerusalem a reminder that norm is Arab terror against Jews (Haar
from the article: Hitler's bodyguard Rochus Misch dies after short illness aged 96