I felt exactly the same way.
The mentioning of Madeleine will drop away.
Swimmers may know him, but more widely he isn't yet a household name and I, for one, would really not have taken much notice of his name had the connection not been made. As his career progresses, (and very best of luck to him on that score!), I am sure his name will stand recognised for his achievements.
A family member lost a child and the emotions are very complicated for all the family, and not necessarily what outsiders might think. It is a leap to say Sean wouldn't want Maddie mentioned.
I thought the photos of his parents and gorgeous sister looking so full of pride and joy were lovely to see, and, for me, it was a reminder that, although Maddie's name has been associated with so much grief over the years, life can bring both sorrow and joy, and I felt it was lovely to see her name scooped up and this time part of such a happy report - almost as if in some way she were part of what I am sure has been a healing process for the family. I bet she'd be proud of her little bro!