I've flown out of McGuire many times, and driven through Mt.Holly. It is a big deal for someone as famous as Kopechne to have been from so small a place. There is a personal connection with that person. It intensifies what people hear about Kennedy. Add to that the Air Force connection. Service people and people with military connections are much more aware than ordinary small town people about the "outside world."
And I'm from a small town. But the point is that Mrs. Alito did not know Mary Jo Kopechne personally. She maybe, possibly, at some point heard about Mary Jo from her husband. And to imagine that Mrs. Alito burst into tears in the middle of her husband's confirmation hearings because of someone she had never met and may have possibly heard about is going too far.