Jacques Goddet, chief reporter of the newspaper L'Auto, took over the organization of the Tour de France in 1936 when its founder Henri Desgrange became too old. Over WW2, Goddet's role was complex. On one hand, L'Auto used its offices to print propaganda for the Resistance. On the other hand, he allowed German occupation forces to use a Velodrome in Paris to intern jewish prisoners. He wrote articles supportive of Pétain's administration. Overall, L'Auto was seen as having been used to support German Nazi activities, under German control.
The end of WW2 saw L'Auto getting shut down, and Goddet launched a new effort called L'Equipe that still exist today, but Goddet was forced to give up control day-to-day control over it.
Since you mentioned Magni, I have to mention Fausto Coppi and Gino Bartali, two fellow Italian cyclists of the same era. Coppi was conscripted into the Italian army after winning his first Giro d'Italia in 1940 at age 20, and ended up getting sent to North Africa as an infantryman. He was captured and sent to a POW camp where he was recognized by several British cycling fans. He survived the war to race again and had his best years post-war.
Bartali, a bit older than Coppi, was allowed to stay in Italy and avoid conscription. He didn't just live an idle life trying to survive the war. He used his fame to help the Italian resistance ferrying secret documents hidden in his bicycle in broad daylight, and helped keep Jewish hideaways in his house.
What an interesting generation of cyclists!