We just have the author's word that the other volunteer was trying to show off and challenge the instructor. He was a volunteer expert, maybe he just thought he

We just have the author's word that the other volunteer was trying to show off and challenge the instructor. He was a volunteer expert, maybe he just thought he and the teacher were partners, and it was their job to discuss high level material for the class. E.g. instructor illustrates no need for semi-colons, meaningful white space -> excited volunteer explains how much cleaner it looks than other programming languages and how great he finds it, maybe with a real world anecdote, or he compares how it is like working with other languages without that, hell maybe even says it isn't a feature he likes, etc.. I'd rather he be open and egregious about his knowledge like this, than just sitting there like a robot for whenever a classmate asks him to help with step 5 or something. It would be a much richer, varied, and more interesting class than some textbook recitation of a tutorial anyone can follow at home anyway.