Joseph:
Why does the fact that they were previously acquainted affect the story? In fact, when I first read the story I assumed that R’ Gustman knew who R’ Aharon was. And the theory about R” Aharon Kotler seems like grasping at straws. First of all who was the milkman? Second of all, there is no particular reason why a story about R’ Aharon Kotler talking about a milkman who knew Shas would somehow evolve into R’ Aharon Lichtenstein volunteering as a milkman, and even more so with the whole rest of the story.
Now I’m not saying the story is true; in fact, there are people who claim that R’ Lichtenstein himself denied it. But the specific points raised by R’ Kahn do not seem particularly compelling.