I think it should be called an interpretation rather than a ruling. It doesn't sound like it's been challenged in either case.

In the case of the F18, I would simply point out the inconsistency in that the rudder pintles/gudgeons are defined in exactly the same way as the foot strap but the rudder hardware (pintles/gudgons) that is bolted to the back of "the hull" has always been excluded from the overall hull length measurement. Why is the foot strap any different if it is defined in the exact same manner?

Then I would get into the weeds with the semantics if that didn't do it.