sorry, it's not my intention to get sucked into this specific deal, but generally speaking, those look like supplemental rules. supp rules only fill in gaps left by the regular rulebook and they only change the regular rulebook if they specifically say so.
there's nothing on that page that says "these supplemental rules redefine what is a dnf in harescrambles." it just says that a DNF doesn't earn you points. if a rider didn't dnf per the regular rulebook, then it's not a dnf. it's a finish.
supp rules aren't the entirety of the rules for a special event or discipline. they only cover unique parts of the special event that haven't already been addressed by AMA Congress. the regular rulebook still applies in areas where it isn't overridden.