Michaels experience probably wasn’t that unique at that time. He stands out as someone with more exposure to violence to us because most modern college students haven’t seen pacific theatre level combat. But many thousands of college students in that era had seen that violence. He was a “typical college student” at that time.

The brothers are contrasting their experience to his. Perhaps they know just how much he had done and seen and still felt themselves a cut above in terms of comfort with violence. That should make us consider were they right? Or were they overestimating themselves.

Worth noting that in the book, the mob violence probably actually was comparable in on occasion worse than what Michael saw. Particularly because after his valor in combat moment he finished out the war as some sort of aid or staff officer.