“Brutal” war stories as pedagogy is… a choice. Assuming the teacher wasn’t a Nazi, I still don’t see how graphic violence is developmentally appropriate math motivation. Might explain why he still acts 12.
Similar story: 7th grade math teacher had left my school unexpectedly and so the principal, who had been in WW2, took over math class.
He told amazing and brutal stories of his time in the war, while also doubling the normal curriculum speed to do 2 years of math in 1.
But if you didn’t do your extra math homework, you didn’t get to hear the stories. Everyone did their homework.