It's not specifically in the rules. However, neither is it in the rules not to use nylon locknuts in any caliper mount (though it makes sense). It's an inspector's call, and no inspector is the same as the next.

We spoke with one of the long time staffers and he said the Accell was originally designed to aim in a safer direction, but that it was moved the day-of for the sake of flatter ground (which he didn't like). He too alluded to the possibilty of a new rule regarding rod-ends, but he had some reservations about dictating such design decisions.