Whilst that does sound a bit bonkers from Willoughby, I reckon there could be something in it. I would not highlight it as an edge as such, but Dettori is the biggest confidence jockey out there riding imo. When things are not going well, I feel he rides with a bit of a chip on his shoulder and can produce some shockers.
When he is in the groove of riding regular quality horses and winning races, he is a far better jockey to have riding your horses.
You only have to read his autobiography to realise how tempremental a character he is. Whether it’s winners that give him confidence on horses, or that he cannot bear being out of the limelight. Probably a little bit of both.