Clever technical interpretation of the rulebook actually. It abides to exactly what the rulebook says -- "The vehicle, unloaded, must be capable of being leaned at an angle of 20 deg. (minimum) from the vertical position without touching the ground, other then the tires, without prior contest board approval)". Thus if they use a wedge type measuring device, I don't see why it wouldn't pass the technical requirement of the rule.
Pretty irrevelent is the fact of how one "leans" that wide front wheel!