Well, If he wrote complex algebra, most if not all end up confused as it wouldn't be easy, and the actual taught life lesson might go over their heads and pupils will have a doubt that the teacher did actually make a mistake in fact so they might be realizing and trust the teacher did it right flawlessly on the instinct. Not the best way and opportunity to teach the kid's life season that as it easy as the equivalent real example needs to be. Meh, it were geometry about fixing X in a certain triangle shape, I wouldn't probably get it at first reading and would more confused and too focus of figuring "how the heck do you solve that mathematical problem" than be aware of "ah ok, good insight! Thx fam" . My point is, examples with complex mathematics isn't the best way to get the point of "ppl are savages - they will make fun of your stupid actions" across.
Also, I think the lesson was stressing more about being strong and getting back on feet when enduring critique, not upon exclusive when you're being praised. There was no mention upon being congratulated on your work.