That's because Schumacher was driving for Ferrari, and from what I can see, they call the shots in F1. They are always the first team in the steward's office complaining if anybody impedes them in any way. In fact I'm still highly suspicious of the part they played in Maclaren's disqualification from the constructors championship.
They didn't suffer for their illegal device that they were forced to remove from their car earlier in the season either.
G