we are supposed to believe that not one of them thought it might be prudent to remain in their seat and refuse to applaud a man who was self-evidently fighting in the Nazi cause?

We are supposed to believe that anyone cared? The people in attendance were almost certainly thinking about what they planned to have for dinner, or wondering about what their kids were doing, or pondering what they might do on the weekend – not listening to what some random nobody who means nothing did a lifetime ago. Not even the strongest-willed person alive would make it through that snooze fest without having their mind wander off.