So she was wrong first. That does not, again does not excuse what he did and it completely wrong and inappropriate to make contact like that with an individual. But the race course is not the place to meet your family. You cross, you get out of the way, you celebrate. Why does she have to interchange the watch with her husband in the middle of the course? He was trying to go for time, she got in the way.
All you need to know about his character is that he sent a letter complaining he was disqualified without an apology. He's within his right to appeal the disqualification, but whether he feels he's wrong or now, a "I am sorry there was contact with another competitor in the course and that is definitely not my intention as another human being should never come above a finish time in a race, or even finishing, or any aspect of the race" should have been the first sentence on that letter, along with a request to pass on the apology to the stricken racer.
It is definitely possible to collide with a racer not on purpose depending on what they do on the course and whether I'm expecting it or not and how much time and space I have to react (and my reaction times may be slower or faster than someone else's), but I would definitely be apologizing profusely, first on the course, then on message boards if I'm seeing it being discussed, and I'd probably not appeal the disqualification and would just chalk it up to being "one of those things" but I would definitely be sending in a letter explaining my side, i.e. didn't expect that, didn't have enough time to react, definitely not my intention for contact, I am sorry for the situation, etc.
Moral of the story: Do not do things you're not supposed to, even if "everybody does it" which seems to be her excuse for something she seems to know that's wrong, and humans are more important than a race.