I think we were supposed to leave the scene with the impression that Peter was a better man than Nathan because he beat Nathan in a fight, which somehow relates to Joshua's belief that Nathan couldn't have killed Suki because he didn't have the guts.
That's a realistic way to portray people's beliefs then, maybe, since I think that attitude was still prevalent when I was a kid. As for PB v. NF, the writers were showing their own prejudice, there. You're reminding me now of my father by bringing this up, and now I'll have to shake that out of my head. I'm sure a lot of damage throughout history has been caused by people assuming that whoever "wins" becomes "right", no matter what the means. That's not really the same thing as what you brought up, but they overlap.
When Nathan was thinking to himself in the beginning, he said that now was the time to be thinking of himself. I wondered: is it ever the time to be thinking solely of oneself?
Interesting. Maybe not. In crises, sometimes, though, there's only so much you may know how to deal with, possibly.