Sadly for Lynn, she couldn't wait to go into depth about what was really going on in the background. We first saw signs of this when she didn't bother to check on the temperature regime Rod would be flying into. She seems to have assumed sight unseen that as soon as Labor Day rolled around, the place would become a frozen hell-world because that's what her high school geography textbooks and any number of Mountie movies implied. This means that she'd convinced herself that Rod was clearly risking his life and risking leaving her a widow going to a place where he couldn't possibly survive and this refusal to be corrected made her angry. Why, she no doubt asked, was her evil father-in-law convinced that doing this horrible thing was a great idea? Why was no one listening to her or obeying her and why were they trying to make her admit she didn't know what she was talking about.
This, I should think, is why the notes point to the conclusion that his near-miss pleased her in a sick sort of way. Rod had an accident and nearly died so she was 'right' to be angry and didn't want to hear evil comments about it being a fluke. She also is still angry because Rod sure doesn't act as if she was right. You and I can live in a world where he bores people to tears with his once cool story of survival. Lynn can't because the innate fear of discomfort that leads her to equate "My mother used to criticize the things I do because she claimed it was the only way I can learn to improve" with "My mother HATES me and wants to TEAR ME APART because I want to be grinning all the time."