Why is the upside down position of the Baucher horse bit not allowed in competitions?

The Baucher bit has but one position and that is with the small rings attached to the bit-hanger straps of the bridle and the reins attached to the large rings as with any snaffle bit. The Baucher is permitted in Hunter, Jumper, and dressage classes.

Attaching a Baucher upside down with the reins attached to the small rings would make it look something like a leverage bit without a chin strap and is inappropriate.