Many who fought the Soviets in the SS did not think what they were doing was wrong. Read up on the Estonian Waffen SS devision. They have a peculiar history. SS Foreign regiments were controversial at the time, and some were declared as non-culpable in the Nuremberg Trails as they were classified as "conscripts". Obviously this man is different, as he volunteered in a regiment that was itself classified as criminal, however it's possible he was expecting similar treatment.