Oy, tough day for everyone...
IF the story is true, it's surprising that at a Worlds, the RC wouldn't AP out of that start with that large a shift making the line so lopsided. Of course, that's a big IF, and to insinuate that's the only reason Besson won is ridiculous.
As for the redress, assuming that the offset was properly set (and on time) and clearly part of the course in the SIs, it's going to be hard to find an error of the RC. It would take a pretty liberal IJ to find that the size of the mark (unless stupidly small) chosen by the RC was an error. It's hard to find liberal IJs, I've observed.