This also demonstrates an uncomfortable situation. There are certain types of bias in favor of women that help out with these kinds of situations. His mom likely was benefitting from a positive bias that she was harmless and fulfilled the presumption about what an inspector may look like... Something like this "Women are wonderful effect"[1]. [1]: https://en.wikipedia.org/wiki/Women_are_wonderful_effect
It's not the pentester's job to fix social policy, merely to point out that threats can come from a variety of vectors that people don't expect.