My grandfather never spoke to me about the Nazi period either. Maybe he would have if I had I asked him but he died before I was old enough to do that.
The reality of it just could not be escaped here though, since just everybody‘s grandparents lived through it. It took up basically half of our whole history curriculum in high school.
So at some point, talking about it in a casual tone became natural. Which is what Arnie is doing here. He’s not glossing over it, to him it just is what it is.