I am glad you are captivated by this shooter/instructors/salesman/ all around upstanding citizen’s comment. But I’m not.
Installing confidence with any pistol the student chooses to show up with is a cornerstone of pistol instruction.
What kind of response would Alvin York and Jim Cirillo have to this, instructor’s, comment? Perhaps this comment is taken out of context. And maybe it is good that this man’s name and associated training facility remain unknown for the good of shooting.
He didn't make the comment in a class setting. It was simply a private conversation. And, like I said, he doesn't even work as an instructor anymore; and that may be because he's not as good an instructor as he is a shooter.
But, as I posted above, his comment is still pretty accurate; there's not a lot of difference between the 9mm, .40, and .45 and you should be prepared to put multiple shots center mass because none of these rounds are magical man-stoppers.